[bluGill]

> You could fit a very respectably battery in the space where the fuel tank and exhaust go

You can fit some battery there, but liquid fuels have a much higher energy density and so I wouldn't call it respectable. I have know people who converted a car to electric, and finding places to stuff batteries was the major challenge, they did the fuel tank of course, but then went looking for any other unused empty space. In the 1980s old trucks were favored because under the bed there was a lot of empty space to work with (even then those old lead-acid batteries didn't give much range)