Electric car batteries have 270 Wh/kg (converts to 0.97 MJ/kg)
Gasoline has 46 MJ/kg
So the math here says electric gives you (0.97 * 77%) 0.75 MJ/kg output and gas gives you (46 * 30%) 13.8 MJ/kg output. Plus, as someone else said, spent gasoline no longer weighs you down.
I like the idea of electric, and I want to see it replace gas as soon as possible, but fair is fair.