Random musing that probably doesn't belong in this topic....but since I'm here:
I wonder if an exhaust can be angled to blow away the oncoming air from the rear wheels, thereby reducing their drag?
It would have to be sufficiently far away from the tyres so that they don't overheat, but a stream of hot fast air will certainly deflect the oncoming air to an extent.
Now I shall wait for the rest of you to give me reasons why this is somehow illegal. Bloody FIA curbing my genius....
Edit:
The Genius misspelled genius.