Re: you can barely turn the undriven wheels by hand
"There are a couple of designs for electrical generation using turbocharger housings - and spinning at 15-25,000 RPM means the entire alternator can be a heck of a lot lighter/simpler."
Nice idea - if your car spends most of its life on the highway. In traffic jams with the engine idling you'll soon find the battery going flat however as the turbo/alternator pack sits there doing virtually nothing.