I guess the definition of "sports car" I was using is a bit fuzzy and esoteric (btw Wally hit the nail in the head).
If there were a toyota camry that could outperform a Corvette in every single performance metric, I'd see it as just a very fast sedan. If I saw a Miata, with is sexy lines and all that, I'd think "oh! a sports car!". Performance obviously makes a sports car, but for the purposes of this topic I guess there was also an emotional element. The sort of car that has "sexy" lines, and is probably not very practical, is a sports car. These are the kind of cars many of us would have in a poster or as a cover in our middle school notebooks, cars such as ferraris, corvettes, porsches and well, technically, the lines of a 240sx or a miata fill the bill too.