Greenhouse officials look at cutting speed limit
Government officials are looking at cutting the speed limit by 10kmh - and charging motorists to drive in urban centres - as ways of cutting greenhouse gas emissions.
Ref. https://www.stuff.co.nz/4513470a10.html
This is old old old news cars from the very start have been design for optimal fuel consumption at 90 to accommodate 80 of the small highway and 100 on the freeways.
If they drop it on the freeway then they need to increase it on the highways. I do not know the starts but I guess the freeway is likely the larger traffic volume of the two.
A wiser approach is to toss in another gear that would let a person hit optimum rpm on the 80 km and change the existing gear to hit the optimum at 100 km. Then enforce the speed limits. Not just speeders but the slow pokes who cause even more traffic issue then the speeders, but never get nailed for it.
I agree get some of the slow pokes off the road that are creating more of a hazard as you have to wait to pass them and use more fuel in the meantime because your vehicle is not running at its peak performance speed. Thus your using more gas than you otherwise would not use.