According to website Dengeki Online and translated by MCV, the figures encompass the seven titles released under the Gran Turismo brand since the PSOne original released in 1997.
According to Sony's figures, Gran Turismo 4 has sold over 10 million copies itself, with the latest release, Gran Turismo 5 Prologue, already shifting over 2.23 million copies worldwide.
Speaking of the achievement, Gran Turismo series producer Kazunori Yamauchi said: "Gran Turismo was made as an 'outsider', to be an alternative to the racing games of its time, and we wanted players to realise that. Because of that, I'm absolutely astonished at this 50 million figure.
When you go to a store and buy a game, the period between picking it up and paying is short - maybe three minutes. It's not easy to think that, in these ten years, that process has been repeated 50 million times.
"I really want to thank all of those people who have supported Gran Turismo with their passion and love up until now. From here on, we'll continue to put all of our effort into making high quality games that don't betray everyone's expectations."