It won't charge appreciably. You might get some slight range extension, but, in the end, resistance, drag, friction, and efficiency will make it not worth it.
The problem is that the wind turbines will not only cause extra drag, but won't be efficient enough, especially if they're packaged within a workable car (I imagine a 200 foot diameter propeller would have issues getting under bridges - that's why they send them one blade at at time to the work site.) to add an appreciable charge - in fact they'll turn slower under load (since generators do offer electrical resistance to rotational motion) and the bigger the deficit between free-speed and load-speed, the more drag you get from the turbine, and thus the more forward energy is wasted in eddy currents and heat.
It seems like a workable idea at first, doesn't it? You'd have something like a perpetual motion machine - but when you get down to it, the laws of energy conservation forbid it from happening. You might get a couple more miles out of a charge - truly dismal performance.
