If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf

On 16/09/2020 22:46, Andy Burns wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf


I am not sure that a study of American cars is particularly relevant fo
UK roads. Many petrol V8s and not very aerodynamic body shapes.


--
Michael Chare

Michael Chare wrote:

I am not sure that a study of American cars is particularly relevant fo
UK roads.Â* Many petrol V8s and not very aerodynamic body shapes.

Maybe not, but it was what I could find.

On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy Burns wrote:

If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf

It's well known that cars give better mpg at 60 than 70, so an improvement in total NOx output can be expected.

Of course speed isn't the only factor. Rate of acceleration & gear use count too.


NT

On 17/09/2020 01:32:48, wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy Burns wrote:

If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf

It's well known that cars give better mpg at 60 than 70, so an improvement in total NOx output can be expected.

No its not.

Of course speed isn't the only factor. Rate of acceleration & gear use count too.

It shouldn't surprise me to hear you would continually accelerate and
decelerate on roads where everyone else, as per the OP, is doing 60 or
70 at a constant speed.

On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy Burns wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

The main reason is that drag varies with the square of speed.
So going only a little slower causes a significant reduction in fuel consumption.

On 17/09/2020 07:01, harry wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy Burns wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

The main reason is that drag varies with the square of speed.
So going only a little slower causes a significant reduction in fuel consumption.


I suspect that the question is related to a 60mph limit on 4 stretches
of UK motorways that is going to be imposed 24/365 to reduce local air
pollution. I suspect that it will not work because in my (limited)
experience of one of those sections traffic cannot travel at 70mph or
even 60 mph currently during much of the day.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 17/09/2020 07:41, alan_m wrote:
On 17/09/2020 07:01, harry wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy BurnsÂ* wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

The main reason is that drag varies with the square of speed.
So going only a little slower causes a significant reduction in fuel
consumption.


I suspect that the question is related to a 60mph limit on 4 stretches
of UK motorways that is going to be imposed 24/365 to reduce local air
pollution. I suspect that it will not work because in my (limited)
experience of one of those sections traffic cannot travel at 70mph or
even 60 mph currently during much of the day.

But a continuous 60 limit should stop all the accelerating back up to 70
when the gaps open up. I'd still expect a net benefit, even if not the
"theoretical" number.

On 17/09/2020 07:41, alan_m wrote:
On 17/09/2020 07:01, harry wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy BurnsÂ* wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fuel usage at high speeds is dominated by drag forces which scale as the
square of the speed. 16% longer time but burning less fuel.

The optimum cruise speed for a particular vehicle shape can be
determined experimentally if you do a regular particular run and have a
trip computer. For my car it is about 55mph.

The main reason is that drag varies with the square of speed.
So going only a little slower causes a significant reduction in fuel
consumption.


I suspect that the question is related to a 60mph limit on 4 stretches
of UK motorways that is going to be imposed 24/365 to reduce local air
pollution. I suspect that it will not work because in my (limited)
experience of one of those sections traffic cannot travel at 70mph or
even 60 mph currently during much of the day.

A bit like the "smart" motorway signs that say 40mph when you are stuck
in a stationary traffic queue moving slower than walking speed the
posted speed limit becomes irrelevant if you cannot hope to reach it.

--
Regards,
Martin Brown

On Thu, 17 Sep 2020 08:58:24 +0100, Martin Brown wrote:

The optimum cruise speed for a particular vehicle shape can be
determined experimentally if you do a regular particular run and have a
trip computer. For my car it is about 55mph.

But varies by gear. In mine for sixth ("top") an indicated 61 returns
the highest mpg. However around 50 in fith returns an even higher
MPG. Trouble is 50 on a motorway is seriously tedious and
concentration is difficult to maintain. Is there still 30+ miles of
average speed cameras set to 50 on the M6 south of Stoke for smart
motorway work?

--
Cheers
Dave.

On 17/09/2020 02:08, Fredxx wrote:
On 17/09/2020 01:32:48, wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy BurnsÂ* wrote:

If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf


It's well known that cars give better mpg at 60 than 70, so an
improvement in total NOx output can be expected.

No its not.

It might not be that well known by the general public but it is correct.
Drag goes up with the square of the windspeed and from about 50mph
onwards it becomes the dominant factor in fuel usage.

The people who drive with a foot hard down on one or other of brake or
accelerator are the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the bumper
of another vehicle. It is reps with this behaviour that make electric
hybrids a tax dodge rather than an effective measure to save the planet.

--
Regards,
Martin Brown

On Thursday, 17 September 2020 09:24:21 UTC+1, Dave Liquorice wrote:
On Thu, 17 Sep 2020 08:58:24 +0100, Martin Brown wrote:

The optimum cruise speed for a particular vehicle shape can be
determined experimentally if you do a regular particular run and have a
trip computer. For my car it is about 55mph.

But varies by gear. In mine for sixth ("top") an indicated 61 returns
the highest mpg. However around 50 in fith returns an even higher
MPG. Trouble is 50 on a motorway is seriously tedious and
concentration is difficult to maintain. Is there still 30+ miles of
average speed cameras set to 50 on the M6 south of Stoke for smart
motorway work?

There is quite a long bit of 50 mph on the M4 (Port Talbot and west).

I am OK with that when I can set adaptive cruise control and not have to keep checking the speedo.

Noticeably high mpg on that section. As it is auto, gear changes are rare - usually goes to 7 and stays there.

"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake or accelerator are
the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the bumper of another
vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car in
front considerably reduce air resistance and thus raise MPG, certainly
in comparison to the car in front ? Being "sucked along" is, I believe, the
relevant phrase.

Maybe it isn't all just testosterone in action after all; but penny pinching
by drivers who are nevertheless in a bit of a hurry.


michael adams

....




..

In article , michael adams
scribeth thus

"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake or
accelerator are
the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the bumper of
another
vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car in
front considerably reduce air resistance and thus raise MPG, certainly
in comparison to the car in front ? Being "sucked along" is, I believe, the
relevant phrase.


Great idea! We can call it a train;! ... Hang on ....

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article , michael adams
wrote:

"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake or
accelerator are the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the bumper
of another vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car in
front considerably reduce air resistance and thus raise MPG, certainly in
comparison to the car in front ? Being "sucked along" is, I believe, the
relevant phrase.

Behind a large lorry, possibly - behind anotehr car, unlikely

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

Dave Liquorice wrote:

Is there still 30+ miles of
average speed cameras set to 50 on the M6 south of Stoke for smart
motorway work?

Dunno, I'll be sure to check or avoid it if I'm going that way, the last
time I went up the M6 it was a horrid journey.

On 17/09/2020 10:33, Andy Burns wrote:
Dave Liquorice wrote:

Is there still 30+ miles of
average speed cameras set to 50 on the M6 south of Stoke for smart
motorway work?

Dunno, I'll be sure to check or avoid it if I'm going that way, the last
time I went up the M6 it was a horrid journey.

+1

and I usually have to navigate the M25 first before getting to the M6
The joys of living in the wrong part of Essex where the last 50 miles to
home can take almost the same amount of time as driving the previous 150
miles!

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

"charles" wrote in message
...
In article , michael adams
wrote:

"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake or
accelerator are the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the bumper
of another vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car in
front considerably reduce air resistance and thus raise MPG, certainly in
comparison to the car in front ? Being "sucked along" is, I believe, the
relevant phrase.

Behind a large lorry, possibly - behind anotehr car, unlikely

While not an expert, who'd have guessed, surely the air displaced by the
first car wouldn't all have returned before the second car arrived.
Maybe at 20 mph but surely not at 70 mph.

I'm not advocating any of this, but if according to the OP they're
already doing it anyway....


michael adams

....








--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

"Jethro_uk" wrote in message
...
On Thu, 17 Sep 2020 11:52:56 +0100, michael adams wrote:

"charles" wrote in message
...
In article , michael adams
wrote:

"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake
or accelerator are the ones who get worst possible mpg and most
pollution.

They are usually to be found in the outside lane 2m behind the
bumper of another vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car
in front considerably reduce air resistance and thus raise MPG,
certainly in comparison to the car in front ? Being "sucked along" is,
I believe, the relevant phrase.

Behind a large lorry, possibly - behind anotehr car, unlikely

While not an expert, who'd have guessed, surely the air displaced by the
first car wouldn't all have returned before the second car arrived.
Maybe at 20 mph but surely not at 70 mph.

I'm not advocating any of this, but if according to the OP they're
already doing it anyway....

As ever, there's an excellent Mythbusters about saving fuel by driving in
the slipstream ...

So its "Mythcorroboraters" then, in this case

quote

The daredevils on Discovery's Mythbusters demonstrated that if you
followed a big rig by 100 feet, you could decrease your fuel consumption
by 11 percent. The intrepid duo pushed the envelope further by following
a truck at only 10 feet --a dangerous maneuver we don't recommend viewers
try at home!--and managed to decreased their gas consumption by 40 percent
..::WiseBread

quote

https://auto.howstuffworks.com/fuel-...that-truck.htm

Following lorries sounds a bit risky. Although the surface area is greater
the risk of decapitation if you go under the bar at the back is a bit
off-putting. A station wagon or a saloon with a long boot would seem a
far safer bet.

michael adams

....

"Jethro_uk" wrote in message
...
On Thu, 17 Sep 2020 12:14:23 +0100, michael adams wrote:

Following lorries sounds a bit risky.

If you'd trust a mesh network of connected controllers, plus a very
controlled environment, it could just work.

"It definitely will work with absolutely no possibility of failure.
With a £10,000,000" life insurance policy thrown in for free"
might sound a bit better.

michael adams

....

On 17/09/2020 02:08:21, Fredxx wrote:
On 17/09/2020 01:32:48, wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy BurnsÂ* wrote:

If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf


It's well known that cars give better mpg at 60 than 70, so an
improvement in total NOx output can be expected.

No its not.

Sorry I misread the text. You are correct, one would reasonable expect a
harder working engine and hence hotter combustion would have a higher
overall NOx in the exhaust.

On 16/09/2020 22:46, Andy Burns wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf

At cruise speeds Nox/mile will be (inversely) proportional to MPG. Over
a fairly broad range of speeds. Its stop start that wastses fuel and
increases Nox, so get rid of traffic lights and speed limits...

--
New Socialism consists essentially in being seen to have your heart in
the right place whilst your head is in the clouds and your hand is in
someone else's pocket.

On 17/09/2020 07:41, alan_m wrote:
On 17/09/2020 07:01, harry wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy BurnsÂ* wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

The main reason is that drag varies with the square of speed.
So going only a little slower causes a significant reduction in fuel
consumption.


I suspect that the question is related to a 60mph limit on 4 stretches
of UK motorways that is going to be imposed 24/365 to reduce local air
pollution. I suspect that it will not work because in my (limited)
experience of one of those sections traffic cannot travel at 70mph or
even 60 mph currently during much of the day.

Also its by no means correct to say that the better MPG (and lower
NOx/mile) will result from lower speeds anyway. A big engine turning
very slowly is not necessarily at its most efficient. My car reached
optimum mpg between 50 and 60 mph and is still up there at 70. What
kills that is having to put on the brakes....and then get it up to speed
again.

It's more knee jerk reactions based on 'intuition' than scientific
analysis based on data.

--
Theres a mighty big difference between good, sound reasons and reasons
that sound good.

Burton Hillis (William Vaughn, American columnist)

On Thu, 17 Sep 2020 12:14:23 +0100, michael adams wrote:

"Jethro_uk" wrote in message
...
On Thu, 17 Sep 2020 11:52:56 +0100, michael adams wrote:

"charles" wrote in message
...
In article , michael adams
wrote:

"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake
or accelerator are the ones who get worst possible mpg and most
pollution.

They are usually to be found in the outside lane 2m behind the
bumper of another vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car
in front considerably reduce air resistance and thus raise MPG,
certainly in comparison to the car in front ? Being "sucked along" is,
I believe, the relevant phrase.

Behind a large lorry, possibly - behind anotehr car, unlikely

While not an expert, who'd have guessed, surely the air displaced by the
first car wouldn't all have returned before the second car arrived.
Maybe at 20 mph but surely not at 70 mph.

I'm not advocating any of this, but if according to the OP they're
already doing it anyway....

As ever, there's an excellent Mythbusters about saving fuel by driving in
the slipstream ...

So its "Mythcorroboraters" then, in this case

quote

The daredevils on Discovery's Mythbusters demonstrated that if you
followed a big rig by 100 feet, you could decrease your fuel consumption
by 11 percent. The intrepid duo pushed the envelope further by following
a truck at only 10 feet --a dangerous maneuver we don't recommend viewers
try at home!--and managed to decreased their gas consumption by 40 percent
.::WiseBread

quote

https://auto.howstuffworks.com/fuel-...that-truck.htm

I saw somewhere that a lorry at a certain distance behind another one could
reduce fuel but increase it for the leading lorry. I guess that it stops the
air flowing into the gap thus maintaining a higher differential pressure for
the leader.

Following lorries sounds a bit risky. Although the surface area is greater
the risk of decapitation if you go under the bar at the back is a bit
off-putting. A station wagon or a saloon with a long boot would seem a
far safer bet.

michael adams

...


--
Peter.
The gods will stay away
whilst religions hold sway

On Thu, 17 Sep 2020 10:33:13 +0100, Andy Burns wrote:

Is there still 30+ miles of average speed cameras set to 50 on the
M6
south of Stoke for smart motorway work?

Dunno, I'll be sure to check or avoid it if I'm going that way, the last
time I went up the M6 it was a horrid journey.

The M6 is fine north of Lancaster and after the border when it
becomes the M74 almost up to the central belt of Scotland. It's
noticeable how the restrictions on road works changes as you go
north. Down near Manchester, its miles of warning signage, average
speed cameras and concrete barriers between the live lanes and
workers. Bit further up some advance warning "roadworks 3 milles", 50
limit, standard cameras, and cones. Further north "roadwaorks" sign
at 400 yds before the cones start to close the live lane.

--
Cheers
Dave.

On 16/09/2020 22:46, Andy Burns wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf



They had the gantry signs saying "60MPH limit in force to lower
pollution" (or similar) last year on the M1 in South Yorkshire.

I also notice that every now and again the gantry signs where the speed
cameras are located have the national speed limit sign showing. I was
once told that this meant the cameras were operating at a 86MPH speed
limit and so I have reduced my speed to 86MPH when passing them.

The cameras have flashed me 3 times this year when no NSL sign is
showing and I have had no NIPs.



--
Adam

Dave Liquorice wrote:

The M6 is fine north of Lancaster

yes, I think it cleared around there, I was only going up to
Grange-over-Sands, so as the roadworks ended the sun came out and the
scenery improved ...

In message , michael adams
writes

"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake
or accelerator are
the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the
bumper of another
vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car in
front considerably reduce air resistance and thus raise MPG, certainly
in comparison to the car in front ? Being "sucked along" is, I believe, the
relevant phrase.

Maybe it isn't all just testosterone in action after all; but penny pinching
by drivers who are nevertheless in a bit of a hurry.

I must bring that into consideration next time I am being harried in an
outside lane.

--
Tim Lamb

On 17/09/2020 09:37, Martin Brown wrote:

They are usually to be found in the outside lane 2m behind the bumper
of another vehicle. It is reps with this behaviour that make electric
hybrids a tax dodge rather than an effective measure to save the planet.


Or me if the lane to left is clear of the knob on the outside lane. They
have 5 seconds to move over or I undertake.


--
Adam

On 17/09/2020 13:47, The Natural Philosopher wrote:
On 17/09/2020 07:41, alan_m wrote:
On 17/09/2020 07:01, harry wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy BurnsÂ* wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be
reduced
sufficiently to have much overall effect on the total emitted over a
4.5
mile stretch?

The main reason is that drag varies with the square of speed.
So going only a little slower causes a significant reduction in fuel
consumption.


I suspect that the question is related to a 60mph limit on 4 stretches
of UK motorways that is going to be imposed 24/365 to reduce local air
pollution. I suspect that it will not work because in my (limited)
experience of one of those sections traffic cannot travel at 70mph or
even 60 mph currently during much of the day.

Also its by no means correct to say that the better MPG (and lower
NOx/mile) will result from lower speeds anyway. A big engine turning
very slowly is not necessarily at its most efficient. My car reached
optimum mpg between 50 and 60 mph and is still up there at 70. What
kills that is having to put on the brakes....and then get it up to speed
again.

It's more knee jerk reactions based on 'intuition' than scientific
analysis based on data.

well if they go slower and not 80 or 90 it will help

In article ,
Andy Burns wrote:
If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf

NOx is going to vary a great deal depending on the type of engine and
condition of it.

CO2 output does tend to be largely speed dependant. Same as MPG.

--
*If a mute swears, does his mother wash his hands with soap?

Dave Plowman London SW
To e-mail, change noise into sound.

On Thursday, 17 September 2020 02:08:27 UTC+1, Fredxx wrote:
On 17/09/2020 01:32:48, tabbypurr wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy Burns wrote:

If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf

It's well known that cars give better mpg at 60 than 70, so an improvement in total NOx output can be expected.

No its not.

Of course speed isn't the only factor. Rate of acceleration & gear use count too.

It shouldn't surprise me to hear you would continually accelerate and
decelerate on roads where everyone else, as per the OP, is doing 60 or
70 at a constant speed.

making up more silly bs I see

On Thursday, 17 September 2020 09:37:36 UTC+1, Martin Brown wrote:
On 17/09/2020 02:08, Fredxx wrote:
On 17/09/2020 01:32:48, tabbypurr wrote:
On Wednesday, 16 September 2020 22:46:38 UTC+1, Andy BurnsÂ* wrote:

If you travel at 60 mph instead of 70, you'll spend 16% longer time
covering a given stretch, will the NOx emission rate per mile be reduced
sufficiently to have much overall effect on the total emitted over a 4.5
mile stretch?

Fig 5 of this seems to show under a 10% factor on the NOx between the
relevant speeds

https://escholarship.org/content/qt01x9w3kf/qt01x9w3kf_noSplash_cbac2ea8aba905cf6ef7d277318129 33.pdf


It's well known that cars give better mpg at 60 than 70, so an
improvement in total NOx output can be expected.

No its not.

It might not be that well known by the general public but it is correct.
Drag goes up with the square of the windspeed and from about 50mph
onwards it becomes the dominant factor in fuel usage.

FWIW it's been well known for a long time.


The people who drive with a foot hard down on one or other of brake or
accelerator are the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the bumper
of another vehicle. It is reps with this behaviour that make electric
hybrids a tax dodge rather than an effective measure to save the planet.

ICBW but AIUI the total cycle of electric versus diesel does not show a convincing 'green' benefit to electric. It does move the pollution away from residential areas to power stations, but that does not achieve 'saving the planet' however the greens choose to define that.


NT

On Thursday, 17 September 2020 09:48:11 UTC+1, michael adams wrote:
"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake or accelerator are
the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the bumper of another
vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car in
front considerably reduce air resistance and thus raise MPG, certainly
in comparison to the car in front ? Being "sucked along" is, I believe, the
relevant phrase.

Maybe it isn't all just testosterone in action after all; but penny pinching
by drivers who are nevertheless in a bit of a hurry.


michael adams

Cyclists sometimes discover just how effective that trick is. They tend to then discover that nothing about pedal bikes is really upto the sort of speeds trucks do.


NT

wrote:


ICBW but AIUI the total cycle of electric versus diesel does not show a
convincing 'green' benefit to electric.

If youd driven into Glasgow yesterday and seen the yellow pall of smog
hanging over the city you might think otherwise.

It does move the pollution away from residential areas to power stations,
but that does not achieve 'saving the planet' however the greens choose to define that.

Volvo/Polestar are trying to put some figures to it all (which account for
carbon costs of build & use).

https://www.polestar.com/uk/electric.../transparency/

Tim


--
Please don't feed the trolls

On Saturday, 19 September 2020 22:23:04 UTC+1, Tim+ wrote:
tabbypurr wrote:


ICBW but AIUI the total cycle of electric versus diesel does not show a
convincing 'green' benefit to electric.

If youd driven into Glasgow yesterday and seen the yellow pall of smog
hanging over the city you might think otherwise.

It does move the pollution away from residential areas to power stations,
but that does not achieve 'saving the planet' however the greens choose to define that.

Volvo/Polestar are trying to put some figures to it all (which account for
carbon costs of build & use).

https://www.polestar.com/uk/electric.../transparency/

Tim

Any genuine comparison is fairly complex, involving a bunch of debateable figures. The error margin gets too large.


NT

wrote:
On Saturday, 19 September 2020 22:23:04 UTC+1, Tim+ wrote:
tabbypurr wrote:


ICBW but AIUI the total cycle of electric versus diesel does not show a
convincing 'green' benefit to electric.

If youd driven into Glasgow yesterday and seen the yellow pall of smog
hanging over the city you might think otherwise.

It does move the pollution away from residential areas to power stations,
but that does not achieve 'saving the planet' however the greens choose to define that.

Volvo/Polestar are trying to put some figures to it all (which account for
carbon costs of build & use).

https://www.polestar.com/uk/electric.../transparency/

Tim

Any genuine comparison is fairly complex, involving a bunch of debateable
figures. The error margin gets too large.

So your assertion is equally debatable...

Tim

--
Please don't feed the trolls

In message ,
writes
On Thursday, 17 September 2020 09:48:11 UTC+1, michael adams wrote:
"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake
or accelerator are
the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the
bumper of another
vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car in
front considerably reduce air resistance and thus raise MPG, certainly
in comparison to the car in front ? Being "sucked along" is, I believe, the
relevant phrase.

Maybe it isn't all just testosterone in action after all; but penny pinching
by drivers who are nevertheless in a bit of a hurry.


michael adams

Cyclists sometimes discover just how effective that trick is. They tend
to then discover that nothing about pedal bikes is really upto the sort
of speeds trucks do.

Umm.. With a 12 tooth fixed wheel sprocket, I could follow the school
bus in the displaced air return. I don't suppose the diesel smoke did my
lungs much good but this was 1958 or thereabouts.

--
Tim Lamb

Tim Lamb wrote:
In message ,
writes
On Thursday, 17 September 2020 09:48:11 UTC+1, michael adams wrote:
"Martin Brown" wrote in message
...

The people who drive with a foot hard down on one or other of brake
or accelerator are
the ones who get worst possible mpg and most pollution.

They are usually to be found in the outside lane 2m behind the
bumper of another
vehicle.

With all due respect wouldn't driving 2m behind the bumper of the car in
front considerably reduce air resistance and thus raise MPG, certainly
in comparison to the car in front ? Being "sucked along" is, I believe, the
relevant phrase.

Maybe it isn't all just testosterone in action after all; but penny pinching
by drivers who are nevertheless in a bit of a hurry.


michael adams

Cyclists sometimes discover just how effective that trick is. They tend
to then discover that nothing about pedal bikes is really upto the sort
of speeds trucks do.

Umm.. With a 12 tooth fixed wheel sprocket, I could follow the school
bus in the displaced air return. I don't suppose the diesel smoke did my
lungs much good but this was 1958 or thereabouts.


Yep. Slipstreaming tractors, lorries & buses was something I did often in
my youth. Theyre all too fast these days though!

Tim

--
Please don't feed the trolls

On 19/09/2020 22:22, Tim+ wrote:
Volvo/Polestar are trying to put some figures to it all (which account for
carbon costs of build & use).

https://www.polestar.com/uk/electric.../transparency/


Good link. Thanks.

"The break-even point shows how far you have to drive in a Polestar 2
before its carbon footprint becomes smaller than a Volvo XC40.

Global power mix: 112,000 km
European power mix: 78,000 km
Wind power: 50,000 km"

It's not worth my wife getting an electric then.

Andy