Gran Turismo (グランツーリスモ Guran Tsūrisumo?, also previously known as Gran Turismo 4 Mobile,[3] Gran Turismo Mobile,[4] Gran Turismo 5 Portable and Gran Turismo Portable) is a 2009 PlayStation Portable (PSP) game developed by Polyphony Digital. The game was announced at the E3 Sony press conference on May 11, 2004, the same conference where Sony announced the original PSP. Following five years of delays and speculation, it made a reappearance at E3 on June 2, 2009 in a playable form. It was released on October 1, 2009 as one of the launch titles for the new PSP Go. As of March, 2013, Gran Turismo has sold 4.22 million units, making it one of the best-selling PSP games.[5] On June 1, 2010, the game was rereleased as part of the Greatest Hits.