You’re underestimating the power requirements to move a car. The tiny BMW i3 range extender package (34hp, 650cc, 2 gallon tank, generator) adds 265lbs to the car. 34hp is 25kW. Normal home-owner generators have a much worse power/weight ratio. My 5500w Generac is 180lbs. You’d be lucky to go 25mph on a flat road...