Shipments of the Gran Turismo series of car racing games edged past the 50 million unit mark at the end of April, Sony said Friday.

The feat places Gran Turismo as the ninth best-selling franchise of all time, ahead of Donkey Kong's 48 million but behind Zelda's 52 million, Grand Theft Auto's 70 million, and Mario's 200 million (Wikipedia).

Gran Turismo was first launched in December 1997 for the original PlayStation console and has been through six incarnations since then. The seventh game in the series, Gran Turismo 5 Prologue for the PlayStation 3, was launched in December 2007.

The game differentiates itself from the myriad of other racing games available for the PlayStation with its realistic simulation of driving a racing car. Sony takes care to ensure that even features such as the engine noise is realistic to the car being driven, and winning is much more complex than hitting the accelerator and beating the other cars.

This attention to detail seems to have caught on with gamers, who made the first version a hit with sales of 10.8 million copies. The second version went on to sell 9.4 million copies and the third version, Gran Turismo 3 A-Spec, became the best selling in the series with sales of 14.8 million copies. The latest version has so far seen sales, which for this title include downloads, of 2.2 million copies.

Despite the success there have been some hiccups along the way, usually in the form of delays.

The new Gran Turismo titles for both the PlayStation 3 and PlayStation Portable have both seen their launch dates pushed back. Gran Turismo 5 for the PlayStation 3 won't be out for at least another year, Sony said in March this year, while Gran Turismo 4 for the PSP isn't due out until 2009.