I put pizza pan wheel covers on my Mustang for several months. Unlike some people's results, they made
no noticeable difference in fuel economy on my Mustang. And chicks didn't dig 'em. I took 'em off.
As for the under-drive crankshaft pulley, it would have been quite time-consuming to do A-B-A testing, so I just did A-B testing. "B" FTW. ~3% gain in MPG. It'll pay for itself in fuel savings in ~150K miles.
In the mean time, I've got bragging rights. I'm averaging over 32 MPG with a 4-liter Mustang.
