Thinking out loud... I would expect that you have pretty laminar flow over the sides of the vehicle, right down at the surface. I would expect the minor depressions for the screw heads and the slots to have very little effect due to this. They might have somewhat more of an effect if the screw hole is deeply recessed, though.
I'm not sure about the front, but the air speed at the front is typically lower than the sides, so any real penalty from a lack of smoothness there would likely be reduced. And the "non smoothness" is pretty darned small anyway.
If you're really really trying to get every last bit out of the car that you can, go for it. It shouldn't be any real appreciable weight (compared to the rest of the car), and if you're careful you can avoid having part of the tape sticking out into the windstream. But my guess is that it probably won't have a noticeable effect.
-soD
|