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.