Exactly, and just because it's so slow doesn't make it not a sports car.
It's a relative term, with a few simple rules to qualify;

A sports car is kind'a like a "supermodel." Most all supermodels are pretty hot. Though there are some that are pretty ugly too. And just because they are ugly to me or you, doesn't make them not a supermodel. The fact that they actually are supermodels is what makes them supermodels, ugly or hot.

A sports car is like that. There are fast/hot ones and slow/ugly ones, slow/hot ones and fast/ugly ones, but the bottom line is, they were developed to be sports cars, not economy or passenger vehicles.
Their specific intent is not always balls-out performance rather than, to be sexy, specifically impractical, and make people envy you when you drive them. Much like having a supermodel for a girlfriend.