Yeah, they do SAE contests at colleges trying to get ultra high mileage vehicles.
They get to do things that wouldn't work in the real world:
-Burn and Coast (get up to speed, kill the engine, coast down to a near stop)
-Drive without concern for normal speeds on highways(really slow)
-Have torpedo like shape
-one passenger only, no cargo, no creature comforts, no safety features
-tiny narrow wheels like a road racing bicycle
I know it's not what you referred to, but I think some of the real-world limitations being removed may be similar.