First of all, looks. A supercar has to be visually arresting, needs to attract attention when standing still, in a parking lot or at the side of the road. A car enthusiast will walk over to it, peer round it, check its lines are as dramatic in the metal as they were when he drooled over them in his regular motoring magazine. But a true supercar will also catch the eye of those who have little interst in great feats of motor engineering. On the move, the real test of a car's visual appeal is whether it attracts attention from drivers travelling in the opposite direction on a motorway. If their eyes are drawn across six carriageways to your vehicle (or if they hang out the window to take pictures), you're in a supercar.