Professional Title: European Editor, Autoblog
There are terms we use in the automotive industry that are easy to define, and those that aren't. Though the lines between various body styles and segments are getting blurred all the time by four-door coupes like the Porsche Panamera or Mercedes CLS, or pseudo-premium/near-luxury marques like Mini or Chrysler, a convertible still has an opening roof, and a pickup truck still has a cargo bed. Supercars, however, are a bit more difficult to define.
So what is a supercar? In this writer's humble opinion, it's a car that's singularly focused on performance with little regard towards other factors like accommodation or cost. It doesn't need to be manufactured by an exotic automaker, but usually is. It similarly doesn't need to be a two-door coupe or convertible, but tends to be.
They also tend to cost more than just about anything else on the road, but all that really matters is how it performs – or rather, how it performs relative to other cars of the same era. So, while even a base Porsche Boxster today might be able to run circles around, say, an original Lamborghini Countach or Ferrari Testarossa, the Lambo and the TR will forever remain supercars – more capable and exotic than most cars in the 1980s – while the Boxster, nimble and superb though it may be, never will. That, after all, is why Porsche made the 918 Spyder.