Seen on the road: a Corolla taxi, with a big, black carbon-fiber spoiler bolted to the trunk hood, along with digital TV and CB-radio antennae. It's a Corolla, I don't think downforce is the biggest handling issue on the list. Given some of the taxis I've ridden in, I'm surprised more aftermarket parts aren't sold in taxi-yellow. Hey, whatever gets you home faster after a night on the town, but there's a reason I prefer to stick to public transportation.
Plenty of American rolling fucktards out there on the road, too, of course, as shown by the picture below.