Elegy is unquestionably best for races with lots of turns, but the Massacro will likely be the best for races with few turns and is almost certainly the best for races with no turns at all (the Carbonizarre used to be best for turn-less races but Massacro unseated it). I have both cars so I'm always prepared, just like I've got the Zentorno and Adder for Supers.
And this talk of the Elegy being moved to Supers is also almost certainly BS, it's the best Sports car all around but it'd make a subpar Super, and someone's comment about the looks being wrong had a point, most (if not all) Supers tend to be more flamboyant than other cars (if they cost as much to make as they do you're not going to want it looking like a normal car, you want people to know you own a half million dollar car just by looking at it). Buffs and nerfs may well happen to bring the cars in line with others in their class, but outright switching classes is highly unlikely to happen.
Well, a dev said that, so we'll see.