Mlts22, I was just thinking not planning on doing anything. You know how we ladies do...I was wondering about effect on MPG but couldn't visualize that they would have that much effect. My thought was the three thin blade ones that are use to produce large power grids. So if not on top how about in front? How about a wind tunnel design, wind goes in turns fan and exits. Rbtglove has a great idea to. This was just an idea to generate;0) some ideas, not trying to develop the greatest money maker since the computer...then again...hmmmmmmmmmm.