Forza Motorsport 5 is the fastest selling of the series, Turn 10 boasted today, thanks to a heavy adoption rate among Xbox One purchasers. The announcement claimed that more than one-third of all XBO owners have a car simulator to go along with it, setting a record for console attach rates for a racing game. To mark the occasion, a track is available for free starting today.

The free track is Road America, and will be automatically added to the Career events. You'll be able to take part in Career events, bonus events, and Rivals and multiplayer races. You can also earn four alternate ribbons through racing on the Road America track.

A Road America "Booster Pack" is also available starting today, free to Car Pass owners. It includes the 2006 #2 Audi Sport North America R8, 1995 Chevrolet Corvette ZR-1, 1968 Ferrari 365 GTB/4, 1971 Ford Mustang Mach 1, and the 2009 Mercedes-Benz SL 65 AMG Black Series.