First of all, I have read some of the previous posts that related to this topic, but they are closed. I am not looking to solve the world's energy crisis, but I was wondering if there was a way to harness some of the energy given off as friction from the drag of a car. I was looking at some of the embellishments on my excursion (clearly not made to be aerodynamic), and I found that there were several different grooves that could easily be made into something like a wind tunnel. So, my question is whether it would increase the drag to cut the ends open and install a small turbine, more so than it could create. Please keep in mind that fact that there is already a preexisting body where it would be, so to simply say "it's impossible due to conservation of energy" is not helpful nor necessarily true. EDIT: I may not have been clear enough as to what I was trying to ask. I would use the turbine as a generator for energy, to be used in the engine in some form or another. Specifically, I was looking at adding a unit that created Hydrogen from water, to enhance the gas and make the car more fuel efficient. But, being that cars are dreadfully inefficient, would it even be worth it in the end? That is, in the sense of energy, not dollars.