High-Fidelity Vehicle Physics

Grip is computed, not assigned. A tyre model converts load, slip angle and surface into force, weight shifts between wheels under braking and cornering, and the drivetrain decides which wheels receive torque, so identical inputs produce different results depending on what the car was doing a moment earlier. Setup values such as gearing, downforce and suspension stiffness feed the same equations, which is what makes tuning consequential.

Polyphony Digital shipped Gran Turismo in 1997 on hardware finally able to run that arithmetic per wheel at frame rate, and paired it with licensed production cars and a career built on buying and modifying them. Serious simulation had existed on personal computers for years in specialist titles, so what 1997 established was that a mass console audience would accept a demanding physical model if the surrounding game was about ownership.

Racing became an equipment hobby, complete with tuning forums, driving-line theory and eventually consumer wheels and pedals, while the same physics work later served open-world games where cars are transport rather than sport. Realism cuts against accessibility, so most series ship assists that quietly simplify the model underneath, and the argument about how much simulation a general audience actually wants has never been settled.