[Nuje]

Wind turbines would certainly not work, as you're adding drag by putting them on, and if my brain is working correctly, I believe it would be impossible for them to produce enough electricity to even make up for how much they slow down your car. As far as only using them when they're useful. For example, you could in theory use them to help slow down your car, while charging your battery (and have them covered, or simply not under load otherwise). However, electric/hybrid cars already have technology in place that recovers electricity while you brake.

Interesting sounding project that you're planning though.