Earlier quoted context omitted.
Actually it's more to do with air resistance. It increases exponentially at higher speeds. You also don't burn less by driving really slow, since the engine burns some amount of fuel just by running at any speed. 40 mph is the sweet spot, supposedly. Driving at the speed limit will definitely save you more fuel than speeding.
> Actually it's more to do with air resistance. It increases exponentially at higher speeds. You also don't burn less by driving really slow, since the engine burns some amount of fuel just by running at any speed. 40 mph is the sweet spot, supposedly. Actually, the sweet spot is dependent on the design and condition of the car. I'm not sure where exactly it is, but I think you are right that it is usually around 40.…
>How does a number on a sign affect how much fuel I'm burning?
I never claimed that it would. I said "Driving at the speed limit will definitely save you more fuel than speeding.", which is definitely true. If you speed you are going faster and using more fuel.