[MetroMPG]

I could list about half a dozen "economy" versions of regular European vehicles, each of which has been lowered (by the factory) by about 10-20 mm as part of a series of mods to improve aerodynamics.

But the other comments (warnings) raised here are valid.

Neil, can you point to a source for the info that there's an optimal ride height? The Top Gear USA project Sipster series also mentioned an optimal ride height, but provided no source (other than their aero "consultant"). I've not read about an optimal ride height before. Seems like too much of a generalization.