There are a total of 5 Death Race movies in the franchise, 6 if you wish to count an unrated film that shared the title.
Death Race (1973), starred Lloyd Bridges, Roy Thinnes, and Eric Braeden; it is the one that's unrelated to the others and it takes place during WWII.
The first of the related death race movies was Death Race 2000; it was released in 1975 and starred David Carradine, Sylvester Stallone, and Simone Griffeth.
The next one was titled simply Death Race; it was released in 2008 and it starred Jason Statham, Joan Allen, and Tyrese Gibson.
Then came a straight to video release titled Death Race 2; it was released in 2010 and starred Luke Goss, Lauren Cohan, and Sean Bean.
The one after that was titled Death Race: Inferno; it was released in 2012 and starred Luke Goss, Tanit Phoenix and Danny Trejo.
Finally, another debuting straight to video is Death Race 3; set for release on January 22, 2013, like DR2, it stars Luke Goss, Danny Trejo, Tanit Phoenix.