Can we classify a smart car with a 500 hp engine a supercar then. It would be really lightweight.
Pony car- goes faster than a base model car, cheaper than a sports car. (Mustang, Camaro, Challenger. Toyota FT-86/Subaru BRZ/Scion FRS would actually make this if it can meet it's price point)
Sports car- goes faster than base model normal car (Anything Z, Corvette)
Supercar- goes faster than a normal car, and you can't afford it (Anything Ferrari, Lambo, Pagani)
Hypercar- goes faster than a supercar, and you weren't worthy enough to be invited to own one. (Bugatti Veyron GS, Lexus LFA)
Exotic car- goes faster than all of the above, they don't make enough for you, and if you've even seen one, you should consider yourself blessed. (Lambo Reventon, Aston Martin One-77)
As with everything in life, there are exceptions to every rule. A Honda Accord can beat an 80's Ferrari 308 to 60 mph, but does that make an Accord a sports car? Does that make the 308 any less special?
Performance is just once measurement of a car, but not the end-all-to-be-all when it comes to the complete overall evaluation of the car. Magnum P.I. had a 308 in Hawaii, and the best you can do is beat him at a stop light in your Accord. Even though the performance is there, no women are gonna drop their pants for an Accord (unless you pay them).
I'd ask you to drop the topic, but to be honest, this debate started way before the first GT, and will end long after the last. However, please keep the debate to those that actually get paid to debate the topic for a living. This topic belongs in a car magazine, not on GT Planet.