Turns out it was one of these -- being driven by some pro-athelete looking guy, which figures I suppose. It always boggles my mind to think of a "high performance exotic" made by Ford, but it has happened from time to time. Of course, he had to park way out in the back forty so that no plebes would come along and ding the fender. ;)
There's a fairly high number of such things floating around here; as a) "the Silicon Valley of the east coast" and b) home to beltway bandits and other evil people, there is always a lot more money than brains. The Lotus Elise seems to be particularly popular in Reston, and various breeds of Ferrari are not uncommon. But what gets me is, between the traffic and the road conditions, you'd never really be able to put a car like that through its paces. So what's the point? It's like the people who buy Hummers to commute to work. Are you fording any rivers? Driving over no-man's-land? No? Then what the heck do you need a 4' ground clearance for?