"Redonda" wrote in message
...
W K wrote:
snip

Ah, I see.
Made up figures then with no facts.

No, not 'made up' figures. Just *my* personal experience in 37 years of
driving including road rallying (in the '60s and '70s with the RAF Motor
Sport Association), 7 1/2 ton trucks and small van deliveries (multi-drop
and long distance). When I've worked for companies with fleets of similar
vehicles I was always able to get better mpg than all the other drivers by
using some of the techniques employed by drivers in the old Mobil Economy
Run (does anyone know if the MER - or its equivalent - still takes
place?).

No science then.
Just figures that you think you remember.

What is the fuel consumption of a modern, standard CAR at 20, 30 and 40?

Do you have any idea.

W K wrote:
"Redonda" wrote in message
...
W K wrote:
snip

Ah, I see.
Made up figures then with no facts.

No, not 'made up' figures. Just *my* personal experience in 37
years of driving including road rallying (in the '60s and '70s with
the RAF Motor Sport Association), 7 1/2 ton trucks and small van
deliveries (multi-drop and long distance). When I've worked for
companies with fleets of similar vehicles I was always able to get
better mpg than all the other drivers by using some of the
techniques employed by drivers in the old Mobil Economy Run (does
anyone know if the MER - or its equivalent - still takes place?).

No science then.
Just figures that you think you remember.

What is the fuel consumption of a modern, standard CAR at 20, 30 and
40?

Do you have any idea.

Enlighten me.

--
Phil ,,,^.".^,,,


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"Redonda" wrote in message
...
W K wrote:
"Redonda" wrote in message
...
W K wrote:
snip

Ah, I see.
Made up figures then with no facts.

No, not 'made up' figures. Just *my* personal experience in 37
years of driving including road rallying (in the '60s and '70s with
the RAF Motor Sport Association), 7 1/2 ton trucks and small van
deliveries (multi-drop and long distance). When I've worked for
companies with fleets of similar vehicles I was always able to get
better mpg than all the other drivers by using some of the
techniques employed by drivers in the old Mobil Economy Run (does
anyone know if the MER - or its equivalent - still takes place?).

No science then.
Just figures that you think you remember.

What is the fuel consumption of a modern, standard CAR at 20, 30 and
40?

Do you have any idea.

Enlighten me.

I don't actually know.

YOU made an assertion that pollution would be greater at 20 than at 40 or
50.
If that assertion has any basis of truth, you could do with telling us.

W K wrote:
"Redonda" wrote in message
...
W K wrote:
"Redonda" wrote in message
...
W K wrote:
snip

Ah, I see.
Made up figures then with no facts.

No, not 'made up' figures. Just *my* personal experience in 37
years of driving including road rallying (in the '60s and '70s with
the RAF Motor Sport Association), 7 1/2 ton trucks and small van
deliveries (multi-drop and long distance). When I've worked for
companies with fleets of similar vehicles I was always able to get
better mpg than all the other drivers by using some of the
techniques employed by drivers in the old Mobil Economy Run (does
anyone know if the MER - or its equivalent - still takes place?).

No science then.
Just figures that you think you remember.

What is the fuel consumption of a modern, standard CAR at 20, 30 and
40?

Do you have any idea.

Enlighten me.

I don't actually know.

YOU made an assertion that pollution would be greater at 20 than at
40 or
50.
If that assertion has any basis of truth, you could do with telling
us.

I doubt there are any facts behind that comment.

Try this for a laugh, swim 10 lengths as fast as you can, then 10 lengths
quite slowly. Which one do you think you've used most energy for? Which
has produced more heat "pollution"? I know cars are very different, but you
still have the basic mechanics of pushing an object through a fluid at
speed.

scott ) gurgled happily, sounding much like they were
saying :

Try this for a laugh, swim 10 lengths as fast as you can, then 10
lengths quite slowly. Which one do you think you've used most energy
for?

I know cars are very different

Erm, yes.

but you still have the basic mechanics of pushing an object
through a fluid at speed.

I don't often drive through "fluid", and my car has more than one gear.

A fairer example would be cycling.

Cycle ten miles, on the flat, at a certain pedal cadence (engine rpm) in
a low gear.

Now cycle ten miles, on the flat, at the same pedal cadence (engine rpm)
in a higher but still comfortable gear.

See the point yet?

If you're cruising (low throttle opening) in a car in a highish gear, at
low revs, that's bound to emit less pollution for a given journey than
similar revs in a lower gear at lower speed - because those revs are
being used for far less time. Assuming the engine's running fairly light
loads, the emissions per minute will be close enough to equal to make no
difference, but if you do the journey in half the time....

"Adrian" wrote in message
. 1.4...
scott ) gurgled happily, sounding much like they were
saying :

Try this for a laugh, swim 10 lengths as fast as you can, then 10
lengths quite slowly. Which one do you think you've used most energy
for?

I know cars are very different

Erm, yes.

but you still have the basic mechanics of pushing an object
through a fluid at speed.

I don't often drive through "fluid", and my car has more than one gear.

A fairer example would be cycling.

Cycle ten miles, on the flat, at a certain pedal cadence (engine rpm) in
a low gear.

Now cycle ten miles, on the flat, at the same pedal cadence (engine rpm)
in a higher but still comfortable gear.

See the point yet?

Yes, the second is far far better for you.
There will be lower forces on legs and muscles.

If you're cruising (low throttle opening) in a car in a highish gear, at
low revs, that's bound to emit less pollution for a given journey than
similar revs in a lower gear at lower speed - because those revs are
being used for far less time.

This assumes the same throttle position.
In all but the slowest of speeds (see below), this will not be the case.

Assuming the engine's running fairly light
loads, the emissions per minute will be close enough to equal to make no
difference, but if you do the journey in half the time....

The speed where this happens is far from obvious.
As I stated elsewhere, the only place I have seen such things discusses was
by people who loved their monstorous 4x4s

W K ) gurgled happily, sounding much like they were
saying :

As I stated elsewhere, the only place I have seen such things
discusses was by people who loved their monstorous 4x4s

*Bzzzzt*

I can't stand "monstrous 4x4s"

Adrian wrote:
scott ) gurgled happily, sounding much like they were
saying :

Try this for a laugh, swim 10 lengths as fast as you can, then 10
lengths quite slowly. Which one do you think you've used most energy
for?

I know cars are very different

Erm, yes.

but you still have the basic mechanics of pushing an object
through a fluid at speed.

I don't often drive through "fluid",

Really? Mastered the art of driving through solids or in a vacuum have you?
;-)

and my car has more than one
gear.

A fairer example would be cycling.

Cycle ten miles, on the flat, at a certain pedal cadence (engine rpm)
in a low gear.

Now cycle ten miles, on the flat, at the same pedal cadence (engine
rpm) in a higher but still comfortable gear.

See the point yet?

Yes, if I go fast cycling I get hot and knackered. I get there quicker but
I've used more energy. If I take it slowly I don't get hot and hence don't
give off as much "heat" pollution. On my bike I can get to about 20mph for
a few minutes at a time, if I drop that to 15mph I can go for *much* longer.

If you're cruising (low throttle opening) in a car in a highish gear,
at low revs, that's bound to emit less pollution for a given journey
than similar revs in a lower gear at lower speed - because those revs
are being used for far less time.

Yes, but you'll be using less petrol. A lower speed = less power from the
engine. This = less pollution.

Assuming the engine's running
fairly light loads, the emissions per minute will be close enough to
equal to make no difference,

How do you work that one out? If I'm using more power to go faster, surely
I need to be using more petrol? As air resistance increases with speed
squared, the amount of petrol used goes up quite quickly once you get to
higher speeds.

scott ) gurgled happily, sounding much like they were
saying :

I don't often drive through "fluid",

Really? Mastered the art of driving through solids or in a vacuum
have you? ;-)

How hard IS it raining where you are? It's quite sunny here.

A fairer example would be cycling.

Cycle ten miles, on the flat, at a certain pedal cadence (engine rpm)
in a low gear.

Now cycle ten miles, on the flat, at the same pedal cadence (engine
rpm) in a higher but still comfortable gear.

Yes, if I go fast cycling I get hot and knackered.

As I said, in a *comfortable* gear.

On my bike I can get to about 20mph for a few minutes at a time, if I
drop that to 15mph I can go for *much* longer.

So let's assume a very low gear and walking speed, and 10-15mph.

If you're cruising (low throttle opening) in a car in a highish gear,
at low revs, that's bound to emit less pollution for a given journey
than similar revs in a lower gear at lower speed - because those revs
are being used for far less time.

Yes, but you'll be using less petrol. A lower speed = less power from
the engine. This = less pollution.

But the engine's turning at the same speed for both. I explicitly said
that. Yes, there's a certain amount more load in the higher gear, but I
also explicitly stated that we weren't talking about a high load
situation akin to your 20mph on your bike.

How do you work that one out? If I'm using more power to go faster,
surely I need to be using more petrol? As air resistance increases
with speed squared, the amount of petrol used goes up quite quickly
once you get to higher speeds.

Which is cancelled out by the higher efficiency of being in a higher
gear. Obviously, there's a point where that's not true, but almost any
car will sit at 40mph or so with virtually no throttle. Try it.

scott wrote:

How do you work that one out? If I'm using more power to go faster,
surely I need to be using more petrol? As air resistance increases
with speed squared, the amount of petrol used goes up quite quickly
once you get to higher speeds.

As I've said before, it depends on the car/engine. My top speed is 130mph
(not had it above 120 - but still plenty of puff left), so at motorway
speeds it's running around 4000rpm (80-ish) with virtually no throttle
applied. A smaller engined car will usually not have much in hand at those
speeds - notice what happens when a small car starts to overtake at the
bottom of a hill. It will usually run out of power and drop back.

Same in town. Smaller engined car drivers are up and down the gearbox to
make progress at speeds varying from 10 to 30mph where I can stay
*comfortably* in 3rd gear through all that range without creating huge gaps
or having to brake sharply.

So. Whose engine is working harder?

--
Phil ,,,^.".^,,,


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