When did diesel cars get complicated?

[norseman]

Lower gears don't increase emissions. It may frustrate progress and it may increase safety. It may also help overall.

I stand corrected, I had assumed that the greater number of revolutions over a given distance would increase both emissions & fuel consumption.

 

[carmanmemoranda]

I stand corrected, I had assumed that the greater number of revolutions over a given distance would increase both emissions & fuel consumption.

2000 rpm (or any other engine speed)
in 1st 2nd or any other gear is still 2000rpm.

Driving at 20mph at 4000rpm for example would be worse than 40mph@2000rpm. But also 30 @3000 would be worse than 20@ 2000 etc

Fuel consumption is worst when accelerating or stood still. Slowly moving traffic would therefore be less bad than stop start traffic. A supposed benefit of lower speed limits in congested areas.

Electric would be better of course

 

[ReganAndCarter]

As said before, I wouldn't get too worried about 20 limits. We've had this for years in Bristol. At first many people stuck to it, but eventually most drifted back to 30. These days you stand out if you stick to the 20 limit and a small queue of cars will form behind you. Only learners and old ladies driving a Honda Jazz stick to 20 now.

 

[norseman]

As said before, I wouldn't get too worried about 20 limits. We've had this for years in Bristol. At first many people stuck to it, but eventually most drifted back to 30. These days you stand out if you stick to the 20 limit and a small queue of cars will form behind you. Only learners and old ladies driving a Honda Jazz stick to 20 now.

That's only human nature, nobody wants to be responsible for holding up traffic & doing so can even invoke the wrath of moronic drivers.
I assume the 20 limit isn't being rigidly enforced ?