I see where you're coming from there Jan, but I think you're missing a fundamental difference in efficiency. An electric powerplant on an aeroplane is around 70-80% efficient, whilst piston engine powerplant is around 15% efficient. So you only need to store for an electric system about 1/5th of the total energy you do in a fuel tank. I'm guessing that there's a similar difference on cars.
The other side of that - and the fundamental problem for electric flight is that the energy storage density of petrol is about 46 MJ/kg, whilst for the very best Li-Ion batteries it's about 0.9 MJ/kg.
So you need 1/5th of the energy (thus allowing sensibleish charging times and very low energy costs) but because energy storage density is about 1/50th - you need 10 times the mass to store energy to do the same amount of work.
On a car, that's bearable within reasonable limits. But the 70L = 50kg of fuel you'd need for an hours flying plus sensible reserves in a PA28 requires around 500kg of batteries. The 450kg difference is all of your available payload, and then some.
G