The Rustler is a WWII fighter plane in Grand Theft Auto: San Andreas, apparently based on the North American P-51 Mustang (Wings, canopy, fuselage) with features derived from the Curtis P-40 Warhawk (empennage, propeller, air scoop) from WWII. It is the oldest aircraft in the GTA series.
It is fast and is quite maneuverable, as expected from a WWII piston engined fighter. It contains 6 machine guns in the wings, and can withstand a lot of punishment.
It is used for most of the missions at the flying school, and for missions with Mike Toreno. It is found in one of the open hangars at Easter Bay International Airport or at the Verdant Meadows airfield.