I haven't witness any documented proofs that Comet can perform well, nobody from Comet master race posted here their results in cutting coroners. Some of them even promised to do that back before update, but their tomorrow is still not here.
In sport class you should consider Elegy, Massacro or Jester.
Comet is, once you understand the mechanics, the most fulfilling car to drive because you can make it do anything when you master steering with the accellerator. The fun comes in knowing when you want to mash it or ease into it, and how to make it work, and in knowing that its a minor difference between looking like Steve McQueen or turning into a James Dean.
Its everything the doriftos want in the game; massive sweeping, ass-out, turns with squeal and smoke and rocketing into the straight when the tires find grip...
But...it simply doesn't have the top speed to keep up with the top tier racers and that combined with the fact that you're always on the edge between control and spin out makes it unreliable in races.
To say nothing of dirty racers.
I used to own the 9f. I believe the hardtop is better, handling wise, than the cabrio. The 9f is alot like the Adder in its control. Its pretty easy to put it into a powerslide and bank around the corner as well, but it does have a tendency to slide if you take it too fast. The 9f is a competent racer, and certainly closer to the top of the sports racers on a track than the Comet is. That said, things like the Jester and Massacro are still better if its strictly for racing.
I no longer own a 9F. I own a Jester for dedicated racing, and a Comet for fun. Further, the Comet is my benchmark for the non-racing garage: If it can't do something better (offroad) or more fun (uncontested) than my Comet, I'll keep it.