Bigwull, it requires very, very little horsepower to move a 75 kilogram (165.3 lbs) mass parallel to the earth’s surface ….. thus the batteries in electric vehicles do a pretty good job at getting “flatlanders” where ever they want to go ….. and back again.
A vehicle’s MPG is calculated on “flatland” driving.
But now Bigwull, it requires one (1) horsepower of energy (745.7 watts) to raise a 75 kilograms (165.3 lbs) mass perpendicular to the earth’s surface, ….. against the earth's gravitational force, …. over a distance of one (1) meter (3.3 ft) in one (1) second. Or in one (1) hour or one (1) day, it doesn’t matter. It doesn’t matter if you stand up real quick like or you take ½ hour to stand up, it still requires the same amount of energy to overcome the force of gravity.
The Nissan Leaf weighs 1,521 kg (3,354 lb) which means it requires a ell of a lot of energy when driving it in hilly or mountainous terrain. More energy than its batteries could possibly supply. Thus a totally electric vehicle would be SOL.