In the last game, the Cheetah was the fastest and had the best handling, the top car. In this game, I say it's either the Bullet or Banshee, but there may be a car I overlooked. My favorite vehicle in this game is the BF Injection, which is pretty fast and has great handling, probably the best next to the Sandking and Monster Truck. The Rancher is great for handling the countryside.
ZR-350 (pretty much the new Infernus), Buffalo, Bullet, Banshee, Turismo, Infernus, Police Car, Cheetah, Elegy, Super GT, muscle cars (which many people overlook, they can be pretty fast and have great handling), Hotring Racer, Uranus, and Flash are all great fast cars.
South Park, Charmed, Buffy The Vampire Slayer / Angel, Tru Calling, Family Guy, TrippingTheRift, FreeForAll, Futurama, Jackass, Lost, That 70's Show, Celebrity Deathmatch