Hi all

On this bright morning I thought to ask you here on r.c.m. if any of
you know what makes the difference for a diesel car between very good
fuel consumption and just good fuel consumption.

The punchline is - where is the extra 30+% fuel consumption going in a
"modern" car?

UK / Europe factor - every car mentioned has manual ("stick-shift")
transmission - five-speed or six-speed.

For nine years, I had a car which reached 20 years of age and went
everywhere, every day, at 63MPG (Imperial 10pint gallon (4.536L); 50.4
miles per US Gallon; 22.2km-per-Litre). With plenty of power -
delight to drive. Turbo spun-up and it surged forward no need for
gear changes.

Even a vibrating rattly tiny Fiat supposed to do 70MPG (Imperial) did
only 55MPG.

My current car mid-range (European style - probably very compact by US
standards) is super luxurious, has a six-speed gearbox, goodly amount
of power - no hills steep enough to keep speed below 70MPH when
cleaning out the engine with sustained accelerator to floor - but
"only" 48MPG (38.4miles per US gallon; 17km per Litre)

A few years ago I was told 60+MPG "is a thing of the past" "with new
emission reg.s" (!!).

The 63MPG car, built in late 1990's, was turbo-diesel, fly-by-wire
diesel injection, probably no filters or anything on the exhaust side
of the engine.
At 63MPG, it cannot have been throwing anything / much out of the
exhaust part-combusted - else it wouldn't be doing 63MPG...
It weighed 1~1/2tonnes - heavy for a smallish compact car.
However, whatever that weight was, it seemed to be involved in
something which nett left you advantaged.
That was 1.9Litres - quite large by UK / Europe standards - where my
more modern car is something like 1.6Litres capacity.
It sounded like a tractor, for sure, when at idle.

That car, the 63MPG car, was Spanish built and badged from the
Volkswagen stable. Someone told me it had the engine from the earlier
VW Golf GTD (turbo diesel performance model). When that was no longer
the new premium model.

So yes, if you could be happy with

a car which sounded like a tractor, you warmed it up slowly to be kind
to the environment, didn't mind that the heaters only worked after
about 3 miles of driving (if you aren't burning much fuel you are not
producing much heat, plus you have a big heavy engine to warm up)

then you got a totally delightful car.

But that fuel consumption... 63MPG (Imperial)
That is the possible.

Where is that extra 30+% fuel going in a "modern" car ???????

The 63MPG (Imperial) shows what is needed to do the job with a
"straight diesel" car. So you can use that as a reference and ask -
for a "modern" car, where is that extra 30+% of "un-accounted-for"
fuel going ???????

I would be very very interested to know.
I've had that question in my mind for since I found I couldn't
like-for-like replace the wonderful VW-family car.

Regards,
Rich Smith

On 30/05/2022 10:57, Richard Smith wrote:
> Hi all
>
> On this bright morning I thought to ask you here on r.c.m. if any of
> you know what makes the difference for a diesel car between very good
> fuel consumption and just good fuel consumption.
>
> The punchline is - where is the extra 30+% fuel consumption going in a
> "modern" car?
>
> UK / Europe factor - every car mentioned has manual ("stick-shift")
> transmission - five-speed or six-speed.
>
> For nine years, I had a car which reached 20 years of age and went
> everywhere, every day, at 63MPG (Imperial 10pint gallon (4.536L); 50.4
> miles per US Gallon; 22.2km-per-Litre). With plenty of power -
> delight to drive. Turbo spun-up and it surged forward no need for
> gear changes.
>
> Even a vibrating rattly tiny Fiat supposed to do 70MPG (Imperial) did
> only 55MPG.
>
> My current car mid-range (European style - probably very compact by US
> standards) is super luxurious, has a six-speed gearbox, goodly amount
> of power - no hills steep enough to keep speed below 70MPH when
> cleaning out the engine with sustained accelerator to floor - but
> "only" 48MPG (38.4miles per US gallon; 17km per Litre)
>
> A few years ago I was told 60+MPG "is a thing of the past" "with new
> emission reg.s" (!!).
>
> The 63MPG car, built in late 1990's, was turbo-diesel, fly-by-wire
> diesel injection, probably no filters or anything on the exhaust side
> of the engine.
> At 63MPG, it cannot have been throwing anything / much out of the
> exhaust part-combusted - else it wouldn't be doing 63MPG...
> It weighed 1~1/2tonnes - heavy for a smallish compact car.
> However, whatever that weight was, it seemed to be involved in
> something which nett left you advantaged.
> That was 1.9Litres - quite large by UK / Europe standards - where my
> more modern car is something like 1.6Litres capacity.
> It sounded like a tractor, for sure, when at idle.
>
> That car, the 63MPG car, was Spanish built and badged from the
> Volkswagen stable. Someone told me it had the engine from the earlier
> VW Golf GTD (turbo diesel performance model). When that was no longer
> the new premium model.
>
> So yes, if you could be happy with
>
> a car which sounded like a tractor, you warmed it up slowly to be kind
> to the environment, didn't mind that the heaters only worked after
> about 3 miles of driving (if you aren't burning much fuel you are not
> producing much heat, plus you have a big heavy engine to warm up)
>
> then you got a totally delightful car.
>
> But that fuel consumption... 63MPG (Imperial)
> That is the possible.
>
> Where is that extra 30+% fuel going in a "modern" car ???????
>
> The 63MPG (Imperial) shows what is needed to do the job with a
> "straight diesel" car. So you can use that as a reference and ask -
> for a "modern" car, where is that extra 30+% of "un-accounted-for"
> fuel going ???????
>
> I would be very very interested to know.
> I've had that question in my mind for since I found I couldn't
> like-for-like replace the wonderful VW-family car.
>
> Regards,
> Rich Smith

Rich,

Sounds like I might have the same engine in a slightly newer 1.9 TDI
Passat and it's still going and hardly doing any mileage these days so
I'm aiming to keep it going as long as possible, last model before DPF
introduction. BTW a UK gallon is 8 pints it's the difference in UK and
US pint sizes that makes the difference
https://en.wikipedia.org/wiki/Pint_glass .

Richard Smith wrote on 5/30/2022 5:57 AM:
> Hi all
>
> On this bright morning I thought to ask you here on r.c.m. if any of
> you know what makes the difference for a diesel car between very good
> fuel consumption and just good fuel consumption.

I am not a regular in this newsgroup but I once owned a VW Jetta TDI,
and I think I am knowledgeable enough on this matter to answer your
question.

Diesel fuel has higher "energy density" than regular gasoline (or
petroleum in the UK). In the oil distillation process in the oil
refinery, diesel fuel is less refined than regular gasoline, and thus
contains more complex hydrocarbon molecules than regular gasoline.
Theoretical a tank of diesel fuel contains more heat energy than the
same volume of regular gasoline if you can burn the fuel thoroughly
through proper combustion.

A diesel engine does not use a spark plug to ignite the fuel in each
combustion cycle. Instead it uses high compression to ignite the
air-diesel mixture, therefore a diesel engine requires stronger metal
components, and thus lasts longer and costs more money to build.

Another advantage of using diesel is that diesel is technically
equivalent to Jet A1 fuel + motor oil. Jet A1 fuel is a common aircraft
engine fuel which is basically a fancy type of kerosene. Because the
less-refined diesel fuel has the engine oil built into it, it actually
lubricates the combustion chamber in each stroke.

With the combined effect of better metal components in building a diesel
engine, a higher energy density of diesel fuel compared to regular
gasoline, and the innate lubricating power of diesel fuel itself, a
diesel engine is renowned to have better fuel economy and last longer.

The disadvantage of using diesel engine in a car is that a diesel engine
is more sluggish in picking up speed compared to a gasoline engine. If
you want jack-rabbit starts after each red traffic light, then a diesel
car will disappoint you.

Diesel engines are the preferred choice for vehicles that require fuel
economy and engine durability. That's why commercial trucks are almost
exclusively diesel.

Hope that helps.

> The punchline is - where is the extra 30+% fuel consumption going in a
> "modern" car?
>
> UK / Europe factor - every car mentioned has manual ("stick-shift")
> transmission - five-speed or six-speed.
>
> For nine years, I had a car which reached 20 years of age and went
> everywhere, every day, at 63MPG (Imperial 10pint gallon (4.536L); 50.4
> miles per US Gallon; 22.2km-per-Litre). With plenty of power -
> delight to drive. Turbo spun-up and it surged forward no need for
> gear changes.
>
> Even a vibrating rattly tiny Fiat supposed to do 70MPG (Imperial) did
> only 55MPG.
>
> My current car mid-range (European style - probably very compact by US
> standards) is super luxurious, has a six-speed gearbox, goodly amount
> of power - no hills steep enough to keep speed below 70MPH when
> cleaning out the engine with sustained accelerator to floor - but
> "only" 48MPG (38.4miles per US gallon; 17km per Litre)
>
> A few years ago I was told 60+MPG "is a thing of the past" "with new
> emission reg.s" (!!).
>
> The 63MPG car, built in late 1990's, was turbo-diesel, fly-by-wire
> diesel injection, probably no filters or anything on the exhaust side
> of the engine.
> At 63MPG, it cannot have been throwing anything / much out of the
> exhaust part-combusted - else it wouldn't be doing 63MPG...
> It weighed 1~1/2tonnes - heavy for a smallish compact car.
> However, whatever that weight was, it seemed to be involved in
> something which nett left you advantaged.
> That was 1.9Litres - quite large by UK / Europe standards - where my
> more modern car is something like 1.6Litres capacity.
> It sounded like a tractor, for sure, when at idle.
>
> That car, the 63MPG car, was Spanish built and badged from the
> Volkswagen stable. Someone told me it had the engine from the earlier
> VW Golf GTD (turbo diesel performance model). When that was no longer
> the new premium model.
>
> So yes, if you could be happy with
>
> a car which sounded like a tractor, you warmed it up slowly to be kind
> to the environment, didn't mind that the heaters only worked after
> about 3 miles of driving (if you aren't burning much fuel you are not
> producing much heat, plus you have a big heavy engine to warm up)
>
> then you got a totally delightful car.
>
> But that fuel consumption... 63MPG (Imperial)
> That is the possible.
>
> Where is that extra 30+% fuel going in a "modern" car ???????
>
> The 63MPG (Imperial) shows what is needed to do the job with a
> "straight diesel" car. So you can use that as a reference and ask -
> for a "modern" car, where is that extra 30+% of "un-accounted-for"
> fuel going ???????
>
> I would be very very interested to know.
> I've had that question in my mind for since I found I couldn't
> like-for-like replace the wonderful VW-family car.
>
> Regards,
> Rich Smith

Mighty Wannabe writes:

> Richard Smith wrote on 5/30/2022 5:57 AM:
>> Hi all
>>
>> On this bright morning I thought to ask you here on r.c.m. if any of
>> you know what makes the difference for a diesel car between very good
>> fuel consumption and just good fuel consumption.
>
> I am not a regular in this newsgroup but I once owned a VW Jetta TDI,
> and I think I am knowledgeable enough on this matter to answer your
> question.
>
> Diesel fuel has higher "energy density" than regular gasoline (or
> petroleum in the UK). In the oil distillation process in the oil
> refinery, diesel fuel is less refined than regular gasoline, and thus
> contains more complex hydrocarbon molecules than regular
> gasoline. Theoretical a tank of diesel fuel contains more heat energy
> than the same volume of regular gasoline if you can burn the fuel
> thoroughly through proper combustion.
>
> A diesel engine does not use a spark plug to ignite the fuel in each
> combustion cycle. Instead it uses high compression to ignite the
> air-diesel mixture, therefore a diesel engine requires stronger metal
> components, and thus lasts longer and costs more money to build.
>
> Another advantage of using diesel is that diesel is technically
> equivalent to Jet A1 fuel + motor oil. Jet A1 fuel is a common
> aircraft engine fuel which is basically a fancy type of
> kerosene. Because the less-refined diesel fuel has the engine oil
> built into it, it actually lubricates the combustion chamber in each
> stroke.
>
> With the combined effect of better metal components in building a
> diesel engine, a higher energy density of diesel fuel compared to
> regular gasoline, and the innate lubricating power of diesel fuel
> itself, a diesel engine is renowned to have better fuel economy and
> last longer.
>
> The disadvantage of using diesel engine in a car is that a diesel
> engine is more sluggish in picking up speed compared to a gasoline
> engine. If you want jack-rabbit starts after each red traffic light,
> then a diesel car will disappoint you.
>
> Diesel engines are the preferred choice for vehicles that require fuel
> economy and engine durability. That's why commercial trucks are almost
> exclusively diesel.
>
> Hope that helps.
>
>
>> The punchline is - where is the extra 30+% fuel consumption going in a
>> "modern" car?
>>
>> UK / Europe factor - every car mentioned has manual ("stick-shift")
>> transmission - five-speed or six-speed.
>>
>> For nine years, I had a car which reached 20 years of age and went
>> everywhere, every day, at 63MPG (Imperial 10pint gallon (4.536L); 50.4
>> miles per US Gallon; 22.2km-per-Litre). With plenty of power -
>> delight to drive. Turbo spun-up and it surged forward no need for
>> gear changes.
>>
>> Even a vibrating rattly tiny Fiat supposed to do 70MPG (Imperial) did
>> only 55MPG.
>>
>> My current car mid-range (European style - probably very compact by US
>> standards) is super luxurious, has a six-speed gearbox, goodly amount
>> of power - no hills steep enough to keep speed below 70MPH when
>> cleaning out the engine with sustained accelerator to floor - but
>> "only" 48MPG (38.4miles per US gallon; 17km per Litre)
>>
>> A few years ago I was told 60+MPG "is a thing of the past" "with new
>> emission reg.s" (!!).
>>
>> The 63MPG car, built in late 1990's, was turbo-diesel, fly-by-wire
>> diesel injection, probably no filters or anything on the exhaust side
>> of the engine.
>> At 63MPG, it cannot have been throwing anything / much out of the
>> exhaust part-combusted - else it wouldn't be doing 63MPG...
>> It weighed 1~1/2tonnes - heavy for a smallish compact car.
>> However, whatever that weight was, it seemed to be involved in
>> something which nett left you advantaged.
>> That was 1.9Litres - quite large by UK / Europe standards - where my
>> more modern car is something like 1.6Litres capacity.
>> It sounded like a tractor, for sure, when at idle.
>>
>> That car, the 63MPG car, was Spanish built and badged from the
>> Volkswagen stable. Someone told me it had the engine from the earlier
>> VW Golf GTD (turbo diesel performance model). When that was no longer
>> the new premium model.
>>
>> So yes, if you could be happy with
>>
>> a car which sounded like a tractor, you warmed it up slowly to be kind
>> to the environment, didn't mind that the heaters only worked after
>> about 3 miles of driving (if you aren't burning much fuel you are not
>> producing much heat, plus you have a big heavy engine to warm up)
>>
>> then you got a totally delightful car.
>>
>> But that fuel consumption... 63MPG (Imperial)
>> That is the possible.
>>
>> Where is that extra 30+% fuel going in a "modern" car ???????
>>
>> The 63MPG (Imperial) shows what is needed to do the job with a
>> "straight diesel" car. So you can use that as a reference and ask -
>> for a "modern" car, where is that extra 30+% of "un-accounted-for"
>> fuel going ???????
>>
>> I would be very very interested to know.
>> I've had that question in my mind for since I found I couldn't
>> like-for-like replace the wonderful VW-family car.
>>
>> Regards,
>> Rich Smith

That is mainly "diesel vs petrol/gasoline".
It's said - half the gain in fuel consumption comes from a higher
thermodynamic efficiency and the other half of the gain comes from
more calorific fuel.

I'm thinking when comparing diesels, where does the about 30% excess
fuel consumption go in diesel vehicles meeting current "emission
regulations".
Obviously the crazy thing is, with global warming yes (amazed when
realise can see it in how high the tides rise compared to previous)
and suspicion our CO2 production could be driving that - why would
higher fuel consumption / more CO2 production be desirable?
I know diesels operate at such a high pressure and temperature that
they do "cook" some of the nitrogen and oxygen together to produce
nitrous oxides - but for reduced CO2 production there looks to be a
balance here. I suspect the answer is run on electric power in cities
and run diesel / fossil-fuel on long runs.

Performance - if you rev-up a diesel and dump the clutch you could if
that was your thing squeal the tyres.
But for day-to-day driving, the fat smooth power delivery of a
turbo-diesel makes for a lovely vehicle to drive especially on our
twisting roads. As you will surely well know with the car you
mention.

On 30/05/2022 10:57, Richard Smith wrote:
> Hi all
>
> On this bright morning I thought to ask you here on r.c.m. if any of
> you know what makes the difference for a diesel car between very good
> fuel consumption and just good fuel consumption.
>
> The punchline is - where is the extra 30+% fuel consumption going in a
> "modern" car?
>
> UK / Europe factor - every car mentioned has manual ("stick-shift")
> transmission - five-speed or six-speed.
>
> For nine years, I had a car which reached 20 years of age and went
> everywhere, every day, at 63MPG (Imperial 10pint gallon (4.536L); 50.4
> miles per US Gallon; 22.2km-per-Litre). With plenty of power -
> delight to drive. Turbo spun-up and it surged forward no need for
> gear changes.
>
> Even a vibrating rattly tiny Fiat supposed to do 70MPG (Imperial) did
> only 55MPG.
>
> My current car mid-range (European style - probably very compact by US
> standards) is super luxurious, has a six-speed gearbox, goodly amount
> of power - no hills steep enough to keep speed below 70MPH when
> cleaning out the engine with sustained accelerator to floor - but
> "only" 48MPG (38.4miles per US gallon; 17km per Litre)
>
> A few years ago I was told 60+MPG "is a thing of the past" "with new
> emission reg.s" (!!).
>
> The 63MPG car, built in late 1990's, was turbo-diesel, fly-by-wire
> diesel injection, probably no filters or anything on the exhaust side
> of the engine.
> At 63MPG, it cannot have been throwing anything / much out of the
> exhaust part-combusted - else it wouldn't be doing 63MPG...
> It weighed 1~1/2tonnes - heavy for a smallish compact car.
> However, whatever that weight was, it seemed to be involved in
> something which nett left you advantaged.
> That was 1.9Litres - quite large by UK / Europe standards - where my
> more modern car is something like 1.6Litres capacity.
> It sounded like a tractor, for sure, when at idle.
>
> That car, the 63MPG car, was Spanish built and badged from the
> Volkswagen stable. Someone told me it had the engine from the earlier
> VW Golf GTD (turbo diesel performance model). When that was no longer
> the new premium model.
>
> So yes, if you could be happy with
>
> a car which sounded like a tractor, you warmed it up slowly to be kind
> to the environment, didn't mind that the heaters only worked after
> about 3 miles of driving (if you aren't burning much fuel you are not
> producing much heat, plus you have a big heavy engine to warm up)
>
> then you got a totally delightful car.
>
> But that fuel consumption... 63MPG (Imperial)
> That is the possible.
>
> Where is that extra 30+% fuel going in a "modern" car ???????
>
> The 63MPG (Imperial) shows what is needed to do the job with a
> "straight diesel" car. So you can use that as a reference and ask -
> for a "modern" car, where is that extra 30+% of "un-accounted-for"
> fuel going ???????
>
> I would be very very interested to know.
> I've had that question in my mind for since I found I couldn't
> like-for-like replace the wonderful VW-family car.
>
> Regards,
> Rich Smith

I forgot to mention in my other post but a mate recently raised the
issue where he was getting noticeably poorer fuel consumption on current
pump diesel than a few years ago. He runs a Nissan SUV, a FIAT camper
van and for work a Ford Transit, all diesel and the vehicles haven't
changed just he isn't getting the same distance out of a tank as he did
a few years back. He mentioned the rumour? that cheap diesel from the
supermarkets doesn’t get you as far and was wondering if the main brands
where he buys his have changed the formulation somehow.

On Mon, 30 May 2022 15:11:57 +0100, David Billington <djb@invalid.com>
wrote:

>On 30/05/2022 10:57, Richard Smith wrote:
>> Hi all
>>
>> On this bright morning I thought to ask you here on r.c.m. if any of
>> you know what makes the difference for a diesel car between very good
>> fuel consumption and just good fuel consumption.
>>
>> The punchline is - where is the extra 30+% fuel consumption going in a
>> "modern" car?
>>
>> UK / Europe factor - every car mentioned has manual ("stick-shift")
>> transmission - five-speed or six-speed.
>>
>> For nine years, I had a car which reached 20 years of age and went
>> everywhere, every day, at 63MPG (Imperial 10pint gallon (4.536L); 50.4
>> miles per US Gallon; 22.2km-per-Litre). With plenty of power -
>> delight to drive. Turbo spun-up and it surged forward no need for
>> gear changes.
>>
>> Even a vibrating rattly tiny Fiat supposed to do 70MPG (Imperial) did
>> only 55MPG.
>>
>> My current car mid-range (European style - probably very compact by US
>> standards) is super luxurious, has a six-speed gearbox, goodly amount
>> of power - no hills steep enough to keep speed below 70MPH when
>> cleaning out the engine with sustained accelerator to floor - but
>> "only" 48MPG (38.4miles per US gallon; 17km per Litre)
>>
>> A few years ago I was told 60+MPG "is a thing of the past" "with new
>> emission reg.s" (!!).
>>
>> The 63MPG car, built in late 1990's, was turbo-diesel, fly-by-wire
>> diesel injection, probably no filters or anything on the exhaust side
>> of the engine.
>> At 63MPG, it cannot have been throwing anything / much out of the
>> exhaust part-combusted - else it wouldn't be doing 63MPG...
>> It weighed 1~1/2tonnes - heavy for a smallish compact car.
>> However, whatever that weight was, it seemed to be involved in
>> something which nett left you advantaged.
>> That was 1.9Litres - quite large by UK / Europe standards - where my
>> more modern car is something like 1.6Litres capacity.
>> It sounded like a tractor, for sure, when at idle.
>>
>> That car, the 63MPG car, was Spanish built and badged from the
>> Volkswagen stable. Someone told me it had the engine from the earlier
>> VW Golf GTD (turbo diesel performance model). When that was no longer
>> the new premium model.
>>
>> So yes, if you could be happy with
>>
>> a car which sounded like a tractor, you warmed it up slowly to be kind
>> to the environment, didn't mind that the heaters only worked after
>> about 3 miles of driving (if you aren't burning much fuel you are not
>> producing much heat, plus you have a big heavy engine to warm up)
>>
>> then you got a totally delightful car.
>>
>> But that fuel consumption... 63MPG (Imperial)
>> That is the possible.
>>
>> Where is that extra 30+% fuel going in a "modern" car ???????
>>
>> The 63MPG (Imperial) shows what is needed to do the job with a
>> "straight diesel" car. So you can use that as a reference and ask -
>> for a "modern" car, where is that extra 30+% of "un-accounted-for"
>> fuel going ???????
>>
>> I would be very very interested to know.
>> I've had that question in my mind for since I found I couldn't
>> like-for-like replace the wonderful VW-family car.
>>
>> Regards,
>> Rich Smith
>
>I forgot to mention in my other post but a mate recently raised the
>issue where he was getting noticeably poorer fuel consumption on current
>pump diesel than a few years ago. He runs a Nissan SUV, a FIAT camper
>van and for work a Ford Transit, all diesel and the vehicles haven't
>changed just he isn't getting the same distance out of a tank as he did
>a few years back. He mentioned the rumour? that cheap diesel from the
>supermarkets doesn’t get you as far and was wondering if the main brands
>where he buys his have changed the formulation somehow.

Thirty percent is pretty big. It would be hard to change diesel oil
that much without causing engine problems. I wonder if the firmware
has been reoptimized for low emission at any cost.

When VW was caught gaming the emissions tests, there was widespread
talk of VW being forced to do exactly such a thing - it was to evade
such a thing the prompted the cheating in the first place.

Joe Gwinn

On Mon, 30 May 2022 10:57:53 +0100, Richard Smith <null@void.com>
wrote:

>Hi all
>
>On this bright morning I thought to ask you here on r.c.m. if any of
>you know what makes the difference for a diesel car between very good
>fuel consumption and just good fuel consumption.
>
>The punchline is - where is the extra 30+% fuel consumption going in a
>"modern" car?
>
>UK / Europe factor - every car mentioned has manual ("stick-shift")
>transmission - five-speed or six-speed.
>
>For nine years, I had a car which reached 20 years of age and went
>everywhere, every day, at 63MPG (Imperial 10pint gallon (4.536L); 50.4
>miles per US Gallon; 22.2km-per-Litre). With plenty of power -
>delight to drive. Turbo spun-up and it surged forward no need for
>gear changes.
>
>Even a vibrating rattly tiny Fiat supposed to do 70MPG (Imperial) did
>only 55MPG.
>
>My current car mid-range (European style - probably very compact by US
>standards) is super luxurious, has a six-speed gearbox, goodly amount
>of power - no hills steep enough to keep speed below 70MPH when
>cleaning out the engine with sustained accelerator to floor - but
>"only" 48MPG (38.4miles per US gallon; 17km per Litre)
>
>A few years ago I was told 60+MPG "is a thing of the past" "with new
>emission reg.s" (!!).
>
>The 63MPG car, built in late 1990's, was turbo-diesel, fly-by-wire
>diesel injection, probably no filters or anything on the exhaust side
>of the engine.
>At 63MPG, it cannot have been throwing anything / much out of the
>exhaust part-combusted - else it wouldn't be doing 63MPG...
>It weighed 1~1/2tonnes - heavy for a smallish compact car.
>However, whatever that weight was, it seemed to be involved in
>something which nett left you advantaged.
>That was 1.9Litres - quite large by UK / Europe standards - where my
>more modern car is something like 1.6Litres capacity.
>It sounded like a tractor, for sure, when at idle.
>
>That car, the 63MPG car, was Spanish built and badged from the
>Volkswagen stable. Someone told me it had the engine from the earlier
>VW Golf GTD (turbo diesel performance model). When that was no longer
>the new premium model.
>
>So yes, if you could be happy with
>
>a car which sounded like a tractor, you warmed it up slowly to be kind
>to the environment, didn't mind that the heaters only worked after
>about 3 miles of driving (if you aren't burning much fuel you are not
>producing much heat, plus you have a big heavy engine to warm up)
>
>then you got a totally delightful car.
>
>But that fuel consumption... 63MPG (Imperial)
>That is the possible.
>
>Where is that extra 30+% fuel going in a "modern" car ???????
>
>The 63MPG (Imperial) shows what is needed to do the job with a
>"straight diesel" car. So you can use that as a reference and ask -
>for a "modern" car, where is that extra 30+% of "un-accounted-for"
>fuel going ???????
>
>I would be very very interested to know.
>I've had that question in my mind for since I found I couldn't
>like-for-like replace the wonderful VW-family car.
>
>Regards,
>Rich Smith
The old car (tdi) cheated on the emissions - google "dieselgate" and
emitted more tiny particles than allowed today. The new car is also
slightly heavier (you said it was more luxurious - so more options and
more sound deadening material) and with a 1.6 liter engine trying to
do the same job the 1.9 did it is working harder - regardless of any
weight increase.

Joe Gwinn <joegwinn@comcast.net> writes:

> On Mon, 30 May 2022 15:11:57 +0100, David Billington <djb@invalid.com>
> wrote:
>
>>On 30/05/2022 10:57, Richard Smith wrote:
>>> Hi all
>>> ...
>>
>>I forgot to mention in my other post but a mate recently raised the
>>issue where he was getting noticeably poorer fuel consumption on current
>>pump diesel than a few years ago. He runs a Nissan SUV, a FIAT camper
>>van and for work a Ford Transit, all diesel and the vehicles haven't
>>changed just he isn't getting the same distance out of a tank as he did
>>a few years back. He mentioned the rumour? that cheap diesel from the
>>supermarkets doesn’t get you as far and was wondering if the main brands
>>where he buys his have changed the formulation somehow.
>
> Thirty percent is pretty big. It would be hard to change diesel oil
> that much without causing engine problems. I wonder if the firmware
> has been reoptimized for low emission at any cost.
>
> When VW was caught gaming the emissions tests, there was widespread
> talk of VW being forced to do exactly such a thing - it was to evade
> such a thing the prompted the cheating in the first place.
>
> Joe Gwinn

30+% is a lot, indeed.
"Gaming the test" - "... has been reoptimized for low emission at any
cost." (sic. - raising fuel consumption so putting out more CO2 is
irrational?)
I did wonder that - keep the performance and low fuel consumption in
all normal driving.

There is a broader endemic issue here that any scheme which "locks
everything down" (sic.) with a tight system of objective rules for an
objective outcome will be gamed. Especially given the tunnel-vision
of those swallowed-up in the rules-based-system, who can't see any
distance that their "paradise they have imposed" is a tiny-distance
illusion.
That is a problem which at the moment is only increasing with
"Standards", "Regulations" (a Law can set a general duty eg. "Safe, so
far is as reasonably practicable" - Regulations can create fractal
nonsense for which there is always a way out saying "we did every
requirement and here is the filing cabinet proving it" when the
reality is something grotesquely different)

Clare Snyder <clare@snyder.on.ca> writes:

> The old car (tdi) cheated on the emissions - google "dieselgate" and
> emitted more tiny particles than allowed today. The new car is also
> slightly heavier (you said it was more luxurious - so more options and
> more sound deadening material) and with a 1.6 liter engine trying to
> do the same job the 1.9 did it is working harder - regardless of any
> weight increase.

The car from the late 1990's was first-principles technically
excellent.
It predated the highly presciptive emissions rules which might have
irrationalities.

Still pondering - where does that extra 30+% of the fuel go?!

Richard Smith wrote on 5/31/2022 3:17 AM:
> Clare Snyder <clare@snyder.on.ca> writes:
>
>
>> The old car (tdi) cheated on the emissions - google "dieselgate" and
>> emitted more tiny particles than allowed today. The new car is also
>> slightly heavier (you said it was more luxurious - so more options and
>> more sound deadening material) and with a 1.6 liter engine trying to
>> do the same job the 1.9 did it is working harder - regardless of any
>> weight increase.
> The car from the late 1990's was first-principles technically
> excellent.
> It predated the highly presciptive emissions rules which might have
> irrationalities.
>
> Still pondering - where does that extra 30+% of the fuel go?!

As I have mentioned before, I owned a VW Jetta TDI that was recalled due
to the VW emission cheating scandal.

I noticed that the speedometer in my Jetta TDI was always 10% above what
was reported by my portable GPS unit I was using in the vehicle.

Since the Jetta TDI was computerized, the manufacturer can easily change
the parameter in the computer to show a 10% higher than normal
speedometer reading (the speedometer reading is proportional to diameter
of the tire for the same rpm.

The end result is that my tank of diesel would travel a fictitious extra
10% distance, and thus inflate the MPG value.

On Tue, 31 May 2022 12:15:40 -0400, Mighty Wannabe
<👩ðŸ?½â€?⚕ï¸?👨â€?⚕ï¸?👮👨ðŸ?¿â€?🚒👷@ðŸ?».ðŸ??🎖ï¸?>
wrote:

>Richard Smith wrote on 5/31/2022 3:17 AM:
>> Clare Snyder <clare@snyder.on.ca> writes:
>>
>>
>>> The old car (tdi) cheated on the emissions - google "dieselgate" and
>>> emitted more tiny particles than allowed today. The new car is also
>>> slightly heavier (you said it was more luxurious - so more options and
>>> more sound deadening material) and with a 1.6 liter engine trying to
>>> do the same job the 1.9 did it is working harder - regardless of any
>>> weight increase.
>> The car from the late 1990's was first-principles technically
>> excellent.
>> It predated the highly presciptive emissions rules which might have
>> irrationalities.
>>
>> Still pondering - where does that extra 30+% of the fuel go?!
>
>As I have mentioned before, I owned a VW Jetta TDI that was recalled due
>to the VW emission cheating scandal.
>
>I noticed that the speedometer in my Jetta TDI was always 10% above what
>was reported by my portable GPS unit I was using in the vehicle.
>
>Since the Jetta TDI was computerized, the manufacturer can easily change
>the parameter in the computer to show a 10% higher than normal
>speedometer reading (the speedometer reading is proportional to diameter
>of the tire for the same rpm.
>
>The end result is that my tank of diesel would travel a fictitious extra
>10% distance, and thus inflate the MPG value.

Tire rolling diameter matters. Were the tires identical to those the
Jetta came with? Correct air pressure?

Joe Gwinn

Joe Gwinn wrote on 5/31/2022 1:01 PM:
> On Tue, 31 May 2022 12:15:40 -0400, Mighty Wannabe
> wrote:
>
>> Richard Smith wrote on 5/31/2022 3:17 AM:
>>> Clare Snyder <clare@snyder.on.ca> writes:
>>>
>>>
>>>> The old car (tdi) cheated on the emissions - google "dieselgate" and
>>>> emitted more tiny particles than allowed today. The new car is also
>>>> slightly heavier (you said it was more luxurious - so more options and
>>>> more sound deadening material) and with a 1.6 liter engine trying to
>>>> do the same job the 1.9 did it is working harder - regardless of any
>>>> weight increase.
>>> The car from the late 1990's was first-principles technically
>>> excellent.
>>> It predated the highly presciptive emissions rules which might have
>>> irrationalities.
>>>
>>> Still pondering - where does that extra 30+% of the fuel go?!
>> As I have mentioned before, I owned a VW Jetta TDI that was recalled due
>> to the VW emission cheating scandal.
>>
>> I noticed that the speedometer in my Jetta TDI was always 10% above what
>> was reported by my portable GPS unit I was using in the vehicle.
>>
>> Since the Jetta TDI was computerized, the manufacturer can easily change
>> the parameter in the computer to show a 10% higher than normal
>> speedometer reading (the speedometer reading is proportional to diameter
>> of the tire for the same rpm.
>>
>> The end result is that my tank of diesel would travel a fictitious extra
>> 10% distance, and thus inflate the MPG value.
> Tire rolling diameter matters. Were the tires identical to those the
> Jetta came with? Correct air pressure?
>
> Joe Gwinn

OEM tires. All four tire specs were exactly as inscribed on the metal
plate inside the door jam. I was the first-hand owner. I'll say it was
deliberate. The speedometer reading cannot deviate by 10% due to tire
pressure.

My portable GPS unit is definitely correct because the speed from that
portable GPS unit always corroborates with the speedometer readings in
all the vehicles I have driven.

On Tue, 31 May 2022 14:14:14 -0400, Mighty Wannabe
<👩ðŸ?½â€?⚕ï¸?👨â€?⚕ï¸?👮👨ðŸ?¿â€?🚒👷@ðŸ?».ðŸ??🎖ï¸?>
wrote:

>Joe Gwinn wrote on 5/31/2022 1:01 PM:
>> On Tue, 31 May 2022 12:15:40 -0400, Mighty Wannabe
>> wrote:
>>
>>> Richard Smith wrote on 5/31/2022 3:17 AM:
>>>> Clare Snyder <clare@snyder.on.ca> writes:
>>>>
>>>>
>>>>> The old car (tdi) cheated on the emissions - google "dieselgate" and
>>>>> emitted more tiny particles than allowed today. The new car is also
>>>>> slightly heavier (you said it was more luxurious - so more options and
>>>>> more sound deadening material) and with a 1.6 liter engine trying to
>>>>> do the same job the 1.9 did it is working harder - regardless of any
>>>>> weight increase.
>>>> The car from the late 1990's was first-principles technically
>>>> excellent.
>>>> It predated the highly presciptive emissions rules which might have
>>>> irrationalities.
>>>>
>>>> Still pondering - where does that extra 30+% of the fuel go?!
>>> As I have mentioned before, I owned a VW Jetta TDI that was recalled due
>>> to the VW emission cheating scandal.
>>>
>>> I noticed that the speedometer in my Jetta TDI was always 10% above what
>>> was reported by my portable GPS unit I was using in the vehicle.
>>>
>>> Since the Jetta TDI was computerized, the manufacturer can easily change
>>> the parameter in the computer to show a 10% higher than normal
>>> speedometer reading (the speedometer reading is proportional to diameter
>>> of the tire for the same rpm.
>>>
>>> The end result is that my tank of diesel would travel a fictitious extra
>>> 10% distance, and thus inflate the MPG value.
>> Tire rolling diameter matters. Were the tires identical to those the
>> Jetta came with? Correct air pressure?
>>
>> Joe Gwinn
>
>OEM tires. All four tire specs were exactly as inscribed on the metal
>plate inside the door jam. I was the first-hand owner. I'll say it was
>deliberate. The speedometer reading cannot deviate by 10% due to tire
>pressure.

OK.

>My portable GPS unit is definitely correct because the speed from that
>portable GPS unit always corroborates with the speedometer readings in
>all the vehicles I have driven.

The standard calibration approach is to use measured one-mile markers
on selected highways. No electronics involved, so clean and direct.

Joe Gwinn

Joe Gwinn wrote on 5/31/2022 4:26 PM:
> On Tue, 31 May 2022 14:14:14 -0400, Mighty Wannabe
> wrote:
>
>> Joe Gwinn wrote on 5/31/2022 1:01 PM:
>>> On Tue, 31 May 2022 12:15:40 -0400, Mighty Wannabe
>>> wrote:
>>>
>>>> Richard Smith wrote on 5/31/2022 3:17 AM:
>>>>> Clare Snyder <clare@snyder.on.ca> writes:
>>>>>
>>>>>
>>>>>> The old car (tdi) cheated on the emissions - google "dieselgate" and
>>>>>> emitted more tiny particles than allowed today. The new car is also
>>>>>> slightly heavier (you said it was more luxurious - so more options and
>>>>>> more sound deadening material) and with a 1.6 liter engine trying to
>>>>>> do the same job the 1.9 did it is working harder - regardless of any
>>>>>> weight increase.
>>>>> The car from the late 1990's was first-principles technically
>>>>> excellent.
>>>>> It predated the highly presciptive emissions rules which might have
>>>>> irrationalities.
>>>>>
>>>>> Still pondering - where does that extra 30+% of the fuel go?!
>>>> As I have mentioned before, I owned a VW Jetta TDI that was recalled due
>>>> to the VW emission cheating scandal.
>>>>
>>>> I noticed that the speedometer in my Jetta TDI was always 10% above what
>>>> was reported by my portable GPS unit I was using in the vehicle.
>>>>
>>>> Since the Jetta TDI was computerized, the manufacturer can easily change
>>>> the parameter in the computer to show a 10% higher than normal
>>>> speedometer reading (the speedometer reading is proportional to diameter
>>>> of the tire for the same rpm.
>>>>
>>>> The end result is that my tank of diesel would travel a fictitious extra
>>>> 10% distance, and thus inflate the MPG value.
>>> Tire rolling diameter matters. Were the tires identical to those the
>>> Jetta came with? Correct air pressure?
>>>
>>> Joe Gwinn
>> OEM tires. All four tire specs were exactly as inscribed on the metal
>> plate inside the door jam. I was the first-hand owner. I'll say it was
>> deliberate. The speedometer reading cannot deviate by 10% due to tire
>> pressure.
> OK.
>
>
>> My portable GPS unit is definitely correct because the speed from that
>> portable GPS unit always corroborates with the speedometer readings in
>> all the vehicles I have driven.
> The standard calibration approach is to use measured one-mile markers
> on selected highways. No electronics involved, so clean and direct.
>
> Joe Gwinn

You'll have to use a stopwatch to time it, then calculate the mile per
second, then convert to mile per hour. That will be a really tedious
task if you don't use a calculator. So you are wrong. Electronics will
be involved.

On Tue, 31 May 2022 08:17:45 +0100, Richard Smith <null@void.com> wrote
as underneath :

>Clare Snyder <clare@snyder.on.ca> writes:
>
>
>> The old car (tdi) cheated on the emissions - google "dieselgate" and
>> emitted more tiny particles than allowed today. The new car is also
>> slightly heavier (you said it was more luxurious - so more options and
>> more sound deadening material) and with a 1.6 liter engine trying to
>> do the same job the 1.9 did it is working harder - regardless of any
>> weight increase.
>
>The car from the late 1990's was first-principles technically
>excellent.
>It predated the highly presciptive emissions rules which might have
>irrationalities.
>
>Still pondering - where does that extra 30+% of the fuel go?!
I think possibly a fair chunk might be because comparative cars seem to
be now much bigger than they were and a lot more comfortable, quieter
etc, and presumably that is what the public wants? Quietness and
comfort (and crash resilience) are weighty and "small" cars now to my
eye are giants in comparison to comparative range models from earlier
years, you might research the comparative weights and aero efficiency.

Charlie+ <charlie@xxx.net> writes:

>>> ...
>> ...
> ...
>
> I think possibly a fair chunk might be because comparative cars seem to
> be now much bigger than they were and a lot more comfortable, quieter
> etc, and presumably that is what the public wants? Quietness and
> comfort (and crash resilience) are weighty and "small" cars now to my
> eye are giants in comparison to comparative range models from earlier
> years, you might research the comparative weights and aero efficiency.

The economical "63MPG" (Imperial gallon) car weighed 1~1/2tonnes
according to the maker's plate - which if so would be quite heavy for
a very modest sized car. ...

On 6/1/2022 12:07 AM, Mighty Wannabe wrote:
> Joe Gwinn wrote on 5/31/2022 4:26 PM:
>> On Tue, 31 May 2022 14:14:14 -0400, Mighty Wannabe
>> wrote:
>>
>>> Joe Gwinn wrote on 5/31/2022 1:01 PM:
>>>> On Tue, 31 May 2022 12:15:40 -0400, Mighty Wannabe
>>>> wrote:
>>>>
>>>>> Richard Smith wrote on 5/31/2022 3:17 AM:
>>>>>> Clare Snyder <clare@snyder.on.ca> writes:
>>>>>>
>>>>>>
>>>>>>>     The old car (tdi) cheated on the emissions - google
>>>>>>> "dieselgate" and
>>>>>>> emitted more tiny particles than allowed today. The new car is also
>>>>>>> slightly heavier (you said it was more luxurious - so more
>>>>>>> options and
>>>>>>> more sound deadening material) and with a 1.6 liter engine
>>>>>>> trying to
>>>>>>> do the same job the 1.9 did it is working harder - regardless of
>>>>>>> any
>>>>>>> weight increase.
>>>>>> The car from the late 1990's was first-principles technically
>>>>>> excellent.
>>>>>> It predated the highly presciptive emissions rules which might have
>>>>>> irrationalities.
>>>>>>
>>>>>> Still pondering - where does that extra 30+% of the fuel go?!
>>>>> As I have mentioned before, I owned a VW Jetta TDI that was
>>>>> recalled due
>>>>> to the VW emission cheating scandal.
>>>>>
>>>>> I noticed that the speedometer in my Jetta TDI was always 10%
>>>>> above what
>>>>> was reported by my portable GPS unit I was using in the vehicle.
>>>>>
>>>>> Since the Jetta TDI was computerized, the manufacturer can easily
>>>>> change
>>>>> the parameter in the computer to show a 10% higher than normal
>>>>> speedometer reading (the speedometer reading is proportional to
>>>>> diameter
>>>>> of the tire for the same rpm.
>>>>>
>>>>> The end result is that my tank of diesel would travel a fictitious
>>>>> extra
>>>>> 10% distance, and thus inflate the MPG value.
>>>> Tire rolling diameter matters.  Were the tires identical to those the
>>>> Jetta came with?  Correct air pressure?
>>>>
>>>> Joe Gwinn
>>> OEM tires. All four tire specs were exactly as inscribed on the metal
>>> plate inside the door jam. I was the first-hand owner. I'll say it was
>>> deliberate. The speedometer reading cannot deviate by 10% due to tire
>>> pressure.
>> OK.
>>
>>
>>> My portable GPS unit is definitely correct because the speed from that
>>> portable GPS unit always corroborates with the speedometer readings in
>>> all the vehicles I have driven.
>> The standard calibration approach is to use measured one-mile markers
>> on selected highways.  No electronics involved, so clean and direct.
>>
>> Joe Gwinn
>
> You'll have to use a stopwatch to time it, then calculate the mile per
> second, then convert to mile per hour. That will be a really tedious
> task if you don't use a calculator. So you are wrong. Electronics will
> be involved.
>

KISS 60 MPH = 60 seconds / 1 minute No electronics, no calculator. Less
than 60 seconds you are going faster than 60 MPH. More than 60 seconds
you are going slower than 60 MPH.

Stan

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On Wed, 1 Jun 2022 00:07:52 -0400, Mighty Wannabe
<👩ðŸ?½â€?⚕ï¸?👨â€?⚕ï¸?👮👨ðŸ?¿â€?🚒👷@ðŸ?».ðŸ??🎖ï¸?>
wrote:

>Joe Gwinn wrote on 5/31/2022 4:26 PM:
>> On Tue, 31 May 2022 14:14:14 -0400, Mighty Wannabe
>> wrote:
>>
>>> Joe Gwinn wrote on 5/31/2022 1:01 PM:
[snip]
>>> My portable GPS unit is definitely correct because the speed from that
>>> portable GPS unit always corroborates with the speedometer readings in
>>> all the vehicles I have driven.
>> The standard calibration approach is to use measured one-mile markers
>> on selected highways. No electronics involved, so clean and direct.
>>
>> Joe Gwinn
>
>You'll have to use a stopwatch to time it, then calculate the mile per
>second, then convert to mile per hour. That will be a really tedious
>task if you don't use a calculator. So you are wrong. Electronics will
>be involved.

Umm, not so fast. Simply check that the car's odometer shows the same
number of miles traveled as the highway mile-markers indicate. No
stopwatch or calculator needed, mechanical or electronic.

Joe Gwinn

"Joe Gwinn" wrote in message
news:oere9h1jttrhl4f80k9k73nbpe0i8130ti@4ax.com...

On Wed, 1 Jun 2022 00:07:52 -0400, Mighty Wannabe
<👩ðŸ?½â€?âš•ï¸?👨â€?âš•ï¸?👮👨ðŸ?¿â€?🚒👷@ðŸ?».ðŸ??🎖ï¸?>
wrote:

>Joe Gwinn wrote on 5/31/2022 4:26 PM:
>> On Tue, 31 May 2022 14:14:14 -0400, Mighty Wannabe
>> wrote:
>>
>>> Joe Gwinn wrote on 5/31/2022 1:01 PM:
[snip]
>>> My portable GPS unit is definitely correct because the speed from that
>>> portable GPS unit always corroborates with the speedometer readings in
>>> all the vehicles I have driven.
>> The standard calibration approach is to use measured one-mile markers
>> on selected highways. No electronics involved, so clean and direct.
>>
>> Joe Gwinn
>
>You'll have to use a stopwatch to time it, then calculate the mile per
>second, then convert to mile per hour. That will be a really tedious
>task if you don't use a calculator. So you are wrong. Electronics will
>be involved.

Umm, not so fast. Simply check that the car's odometer shows the same
number of miles traveled as the highway mile-markers indicate. No
stopwatch or calculator needed, mechanical or electronic.

Joe Gwinn

---------------------------------
The odometer is mechanically coupled to the wheels but an analog speedometer
isn't, and they may not agree.
https://www.howacarworks.com/accessories/how-a-speedo-works

On Wed, 1 Jun 2022 11:55:28 -0400, "Jim Wilkins"
<muratlanne@gmail.com> wrote:

>"Joe Gwinn" wrote in message
>news:oere9h1jttrhl4f80k9k73nbpe0i8130ti@4ax.com...
>
>On Wed, 1 Jun 2022 00:07:52 -0400, Mighty Wannabe
><👩ðŸ?½â€?⚕ï¸?👨â€?⚕ï¸?👮👨ðŸ?¿â€?🚒👷@ðŸ?».ðŸ??🎖ï¸?>
>wrote:
>
>>Joe Gwinn wrote on 5/31/2022 4:26 PM:
>>> On Tue, 31 May 2022 14:14:14 -0400, Mighty Wannabe
>>> wrote:
>>>
>>>> Joe Gwinn wrote on 5/31/2022 1:01 PM:
>[snip]
>>>> My portable GPS unit is definitely correct because the speed from that
>>>> portable GPS unit always corroborates with the speedometer readings in
>>>> all the vehicles I have driven.
>>> The standard calibration approach is to use measured one-mile markers
>>> on selected highways. No electronics involved, so clean and direct.
>>>
>>> Joe Gwinn
>>
>>You'll have to use a stopwatch to time it, then calculate the mile per
>>second, then convert to mile per hour. That will be a really tedious
>>task if you don't use a calculator. So you are wrong. Electronics will
>>be involved.
>
>Umm, not so fast. Simply check that the car's odometer shows the same
>number of miles traveled as the highway mile-markers indicate. No
>stopwatch or calculator needed, mechanical or electronic.
>
>Joe Gwinn
>
>---------------------------------
>The odometer is mechanically coupled to the wheels but an analog speedometer
>isn't, and they may not agree.
>https://www.howacarworks.com/accessories/how-a-speedo-works

Yes. In a given car, the odometer directly reporters cumulative
distance traveled, as integrated from wheel rotation, while the
speedometer includes an added error-adding rate-computation step, so
the odometer will be more accurate than double integrating speedometer
data.

Joe Gwinn

On Wed, 1 Jun 2022 00:07:52 -0400, Mighty Wannabe
<👩ðŸ?½â€?⚕ï¸?👨â€?⚕ï¸?👮👨ðŸ?¿â€?🚒👷@ðŸ?».ðŸ??🎖ï¸?>
wrote:

>Joe Gwinn wrote on 5/31/2022 4:26 PM:
>> On Tue, 31 May 2022 14:14:14 -0400, Mighty Wannabe
>> wrote:
>>
>>> Joe Gwinn wrote on 5/31/2022 1:01 PM:
>>>> On Tue, 31 May 2022 12:15:40 -0400, Mighty Wannabe
>>>> wrote:
>>>>
>>>>> Richard Smith wrote on 5/31/2022 3:17 AM:
>>>>>> Clare Snyder <clare@snyder.on.ca> writes:
>>>>>>
>>>>>>
>>>>>>> The old car (tdi) cheated on the emissions - google "dieselgate" and
>>>>>>> emitted more tiny particles than allowed today. The new car is also
>>>>>>> slightly heavier (you said it was more luxurious - so more options and
>>>>>>> more sound deadening material) and with a 1.6 liter engine trying to
>>>>>>> do the same job the 1.9 did it is working harder - regardless of any
>>>>>>> weight increase.
>>>>>> The car from the late 1990's was first-principles technically
>>>>>> excellent.
>>>>>> It predated the highly presciptive emissions rules which might have
>>>>>> irrationalities.
>>>>>>
>>>>>> Still pondering - where does that extra 30+% of the fuel go?!
>>>>> As I have mentioned before, I owned a VW Jetta TDI that was recalled due
>>>>> to the VW emission cheating scandal.
>>>>>
>>>>> I noticed that the speedometer in my Jetta TDI was always 10% above what
>>>>> was reported by my portable GPS unit I was using in the vehicle.
>>>>>
>>>>> Since the Jetta TDI was computerized, the manufacturer can easily change
>>>>> the parameter in the computer to show a 10% higher than normal
>>>>> speedometer reading (the speedometer reading is proportional to diameter
>>>>> of the tire for the same rpm.
>>>>>
>>>>> The end result is that my tank of diesel would travel a fictitious extra
>>>>> 10% distance, and thus inflate the MPG value.
>>>> Tire rolling diameter matters. Were the tires identical to those the
>>>> Jetta came with? Correct air pressure?
>>>>
>>>> Joe Gwinn
>>> OEM tires. All four tire specs were exactly as inscribed on the metal
>>> plate inside the door jam. I was the first-hand owner. I'll say it was
>>> deliberate. The speedometer reading cannot deviate by 10% due to tire
>>> pressure.
>> OK.
>>
>>
>>> My portable GPS unit is definitely correct because the speed from that
>>> portable GPS unit always corroborates with the speedometer readings in
>>> all the vehicles I have driven.
>> The standard calibration approach is to use measured one-mile markers
>> on selected highways. No electronics involved, so clean and direct.
>>
>> Joe Gwinn
>
>You'll have to use a stopwatch to time it, then calculate the mile per
>second, then convert to mile per hour. That will be a really tedious
>task if you don't use a calculator. So you are wrong. Electronics will
>be involved.
>
>
>
Generally calibrating the odometer on the "quarter" or ":measured
mile" or using the "mileposts" on the freeway handles calibrating the
speedo - as they are generally NOT independent. If the odo is right
you have the right speedo gear or calibration setting

"Clare Snyder" wrote in message
news:ac7g9hdq0o75fc1dic084cbb0uqr0prf7u@4ax.com...

Generally calibrating the odometer on the "quarter" or ":measured
mile" or using the "mileposts" on the freeway handles calibrating the
speedo - as they are generally NOT independent. If the odo is right
you have the right speedo gear or calibration setting

-------------------------
The odometer is mechanically geared to count driveshaft revolutions, the
speedometer reading also depends on balancing spring tension against
magnetic pull. Tire size and wear affects both equally but the
proportionality between them is only as accurate as the speedo's factory
calibration.

If this becomes an issue I have the speedometer from a crashed motorcycle
that I salvaged to build my sawmill. (The owner wasn't hurt.) I cut off the
crimp ring to open the speedometer housing to replace the broken glass and
taped it back together. I could look for a means of calibrating it such as a
clamp on the hairspring but I don't want to change it since it gives me the
bandsaw blade's feet per minute which I watch to adjust feed pressure.

I was a project manager at a company that built custom production test
equipment for the auto industry, so I tried to learn the functional details
of accessory components, which was difficult because the car makers are very
secretive about their methods, even between divisions of the same company. I
can't reveal what inside information I do know because I signed
non-disclosure agreements.

This suggests how to design an automated speedometer calibration station:

https://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/speedometer4.htm

"No speedometer can be 100 percent accurate. In fact, most manufacturers
build speedometers so they fall within a fairly narrow tolerance range, no
more than 1 percent to 5 percent too slow or too fast."

My knowledge of automotive electronics saved me from a lawsuit later since I
could demonstrate that my design was common knowledge instead of a
proprietary secret.

On Thu, 2 Jun 2022 07:24:41 -0400
"Jim Wilkins" <muratlanne@gmail.com> wrote:

<snip>
>The odometer is mechanically geared to count driveshaft revolutions, the
>speedometer reading also depends on balancing spring tension against
>magnetic pull. Tire size and wear affects both equally but the
>proportionality between them is only as accurate as the speedo's factory
>calibration.

Years ago... I installed some after market speakers in the dash of my
Chevy service van. On the drivers side it was a really tight fit. The
speaker magnet was right next to the speedometer housing. After
the speakers went in the speedometer read about half your actual speed.
Around 30mph was actually 60mph. Odometer still read okay.

I messed around with it some trying to get it right again but finally
decided I could live with the odd speedo reading to have the
booming radio ;-)

--
Leon Fisk
Grand Rapids MI

"Leon Fisk" wrote in message news:t7aht0$5j1$1@dont-email.me...

On Thu, 2 Jun 2022 07:24:41 -0400
"Jim Wilkins" <muratlanne@gmail.com> wrote:

Years ago... I installed some after market speakers in the dash of my
Chevy service van. On the drivers side it was a really tight fit. The
speaker magnet was right next to the speedometer housing. After
the speakers went in the speedometer read about half your actual speed.
Around 30mph was actually 60mph. Odometer still read okay.

I messed around with it some trying to get it right again but finally
decided I could live with the odd speedo reading to have the
booming radio ;-)

--
Leon Fisk
Grand Rapids MI
------------------------

I built a prototype receiver/decoder for this system:
https://en.wikipedia.org/wiki/Radio_Data_System

We were assured it would only handle traffic alert messages, not take
control of the car, although it could have.