[Christ]

Originally Posted by Piwoslaw

Very interesting!

I can't find any hi-res pictures of that area through Google, so I'll have to take a closer look next time I see one in a parking lot. It's too bad that I usually don't have a camera with me (In the spirit of waste reduction I still have a stone age cell phone).
My first uneducated guess would be that maybe that bulge somehow controls turbulence in the wheelwell. Sort of like a 'virtual' wheelskirt.
But it may just as well control water spray. These two ideas aren't even mutually exclusive.

Get a smart phone. Reduce your overall energy consumption. Betcha never heardsomeone advertising the green aspect of these wretched contraptions, eh?