rFactor is a computer racing simulator, designed with the ability to run any type of four-wheeled vehicle from street cars to open wheel cars of any era. rFactor aimed to be the most accurate race simulator of its time. Released in November 2005, rFactor did not have much competition in this market; however it featured many technical advances in tire modeling, complex aerodynamics and a 15 degrees of freedom physics engine.
rFactor was developed by Image Space Incorporated (ISI), which has been developing simulators since the early 1990s for both commercial and military purposes. The gMotor-engine2 on which the game is based is a direct successor to the engine used in previous titles developed by ISI, most notably F1 Challenge '99-'02, released through EA Sports. The gMotor2 engine was also used in many Simbin games, including GT Legends, the GTR series and the Race series. A modified version of this engine was utilized by The Sim Factory for ARCA Sim Racing. A special version of rFactor was available for business application, for example for event simulators or promotion.