I know this question was already asked but I wanted to tackle it from a different angle. I saw allot of posts on how it would take too much gas to create the energy from the turbine but for the example lets say the car is electric. Now say we have a system where the turbine is in a tube aerodynamically built into the car, and this tube is opened and closed by pulleys or some such simple system connected to the gas pedals. Oh and the tube closes when the gas pedal is being pushed upon Okay with all of that we have a turbine that only inflicts drag upon the car when the gas is not in use aka when your coasting down hill or braking. Could you use this system to increase "gas" mileage? For example converting the Potential energy of gravity into electricity? Sorry if its a stupid question but i started reading about wind turbines two days ago and this is one of a few ideas that popped into my head, and they haunt me until I get them out.