The Stallion is an old-time convertible muscle car based off of a '60s Ford Mustang. In proper musclecar fashon, it has V8 power channeled to the rear wheels.
It was first featured in GTA3. It's handling changed in each GTA. In GTA3 it was very unstable and highly oversteering, in Vice City the Stallion can do easier drifts and doughnuts, while in San Andreas it is quite stable.