[economusty]

I don't think you have much losses in the transfer, the strap is probably efficient. Although they would be extra so you are correct.

[SomeHacker44]

GP almost certainly meant losses in the transfer from mechanical energy to chemical energy by way of the cars motors being used as generators, then charging the batteries.

[throwaway0a5e]

Don't forget the double loss from sending the rotational energy to the ground and back.

[uncoder0]

Unsprung mass always surprises.