Sony Computer Entertainment America today announced the release of the downloadable version of Gran Turismo 5 Prologue, the fifth installment of the billion-dollar selling racing franchise developed by Polyphony Digital. The game comes with in depth car tuning, which allows players to adjust the vehicle's performance, including power, tyres, suspension and the ability for quick tuning whilst racing, a drift mode and a two-player split screen mode, as well as scheduled race events. Gran Turismo 5 Prologue will be available tonight from PlayStation Store US for 39.99USD.