I say yes.
Lowering the car obviously reduces CdA. This is good.
Tightening the wheel gap reduces air turbulence. Actually, if you look at manufactuers cars from the 90s then the same cars today, you'll notice the fenders are held much tighter to the wheels from the factory - in diameter, not in width. Part of the issue of doing it yourself is that many cars have fenders that have an outer surface not perpendicular to the road - so the closer you move the wheel to being flush up top, the more it sticks out on the bottom. (see this thread:
http://ecomodder.com/forum/showthrea...g-20278-2.html)
I know if I end up going to the FE @ Watkins in April, I'd bring a car that was "stanced" with lower drag in mind.