Expert: Paul Soderman - 11/15/2009

Question
Does a dimpled car having a better mpg a good scientific backing. Is the basis of the idea good? The mythbusters tested it and found that it worked. I was wondering if there is evidence that this would work. http://dimpledcar.com/

Answer
I don't know but I am dubious.  First, the dimples look pretty big - they would be creating a lot of turbulence.  A little turbulence is good just upstream of a flow separation region like the small dimples on a golf ball.  That can delay separation and reduce drag.  But a lot of turbulence is bad, especially in places where it is unnecessary such as the front bumper or front door -  far from the aft separation regions.  This is why wind tunnels are good - such things can be tested.  Or you do a careful drive test.  If this is really a good idea, that data and details on how they got the gas savings would be made available.
Paul