reshaping the roof
 

i've got acouple of questions regarding roof ridges(ie. the indents put in the roofs of vans, mini vans, suv's roofs)


1; would removing them lower/raise cd?
2; effect fuel economy?(positively or negatively)
3; ways of "removal"?(filling them in, taping over)

In my opinon, it isn't gonna make enough of a difference to even give it much thought. Often those ridges are simply to provide structural strength. They keep the roof from smooshing in when you get say 2 feet of snow on it. They are always aligned with the slip stream, and their profile is so low, they have very little impact.

I think if you were to design a raised roof that went up several inches maybe a foot about 1/3rd the way back and have it taper to the front sides and overhang the back you might improve the cda. I figure that in big part the air is turbulent once it gets past the windshield on most any traditional vehicle.