[ptack]

Mythbusters put dimples on a car and did find an 11% improvement in efficiency, but as written above, F1 is not just about efficiency. It's also possible that this effect is very speed and scale dependent meaning the dimples would have to change size as speed changes. That said, unless it's specifically against the rules, I would not be surprised if you end up seeing some surfaces with dimples or other textures to selectively affect the movement of air. They are already doing the vortex generators. It's also possible that the incremental improvements don't justify the high design/computing costs - yet.