that is a myth along with insurance being higher for red cars.
I know a lot of cops and I asked them that question....they have all told me that red is NEVER a signal to pay more attention to a car verse another car that is white or black or whatever.
afterall, you can get minivans in red and I have never seen a minivan driver be all about speed because they are in their red minivan.
you can also google the myth and find site after site dispelling the myth...including snopes. http://www.snopes.com/autos/law/redcars.asp
As a naturally suspicious person...most people who are suspicious drive black vehicles.IMO.