The mountainous roads surrounding Virginia's Shenandoah Valley aren't the world's most treacherous, but they are fun to drive, and they're easy to get to from Washington, D.C. So it's not all that surprising that car enthusiasts from the D.C. area's teeming, affluent suburbs occasionally make their way down there.

Many states populate their highways with ominous 'Speed Limit Enforced By Aircraft' signs — as if squadrons of F-16s fly overhead waiting to pop motorists for going 10 mph over the speed limit. While there are states that still use planes to enforce the speed limit, there's one member of the Union that mostly just…