I am in no position to argue with people who have engineering knowledge, but I don't think that analogy applies, since a car is not being driven by wind as a sailboat is. (Again, I know I am going to be shot down on this.)

I was visualizing a flat (horizontal), and very efficient wind turbine in a very low-profile, aerodynamic casing, maybe molded into the roof. Or it could even be contained within the front of the car itself, rather than on the roof. Isn't air going into the engine compartment through the grill anyway?

What I am thinking about shouldn't increase drag any more than a side rear-view mirror. So eliminate one of those to compensate.

Some inventions would never have happened if the inventors listened to the people who said, "It can't be done."

Here's another one. You could have pedals inside your electric car so the passengers could pedal while you are driving and keep adding electricity to the battery. And get exercise at the same time.

Sorry, but it's fun for me to think about all these things.