Future High Mpg Cars Future Cars: Could You Live By Going A Max Speed Of 40 MPH On The Highway?

Future cars: Could you live by going a max speed of 40 MPH on the highway? - future high mpg cars

I believe that the earth be nice if we had had, dass

Small high-tech petrol or diesel engine 200 can MPG. But it's no problem, you must have a maximum speed of 40 mph

The only problem would be slow speed. What do you think?