Everywhere i have read about people that want to decrease their qt. mile time i have heard to remove your rear bumper. Said to give at least a .1 decrease off your time. Well, I was wondering what if you mounted a plate underneath the car to stop air from being trapped at the rear bumper. I know that i have heard of a few people doing this, so could anyone share their results. Also, would it be best to use a flat surface or a dimpled surface? Would creating turbulent flow underneath the car w/ the dimpled be a good idea? How would that react at 125-130mph? Any thoughts, advice, corrections?

 

You probably want it smooth to decrease resistance. Dimpled might work on a golf ball but I don't think it would work on a flat surface.

As to whether it will actually make a difference, I don't know but doubt it. Quarter mile times are mostly changed by acceleration at lower speeds. 0-60 is much more important than 100-130 for instance, and that's talking if the plate even did anything noticeable at those speeds.