No DLC for Forza Horizon 2 on Xbox 360
It has been confirmed by Turn 10 that there will be no DLC for Forza Horizon 2 on Xbox 360. On the game’s forums, the community manager Brian Ekberg has specified that Forza Rewards are only for the Xbox One owners.
Forza Rewards benefits are only available in the Xbox One version of Forza Horizon 2. This means that Xbox 360 players will not receive Forza Rewards credits or cars.
Also, your progress in the 360 version of the Forza Horizon 2 will not count for your Forza Rewards Tier Level score. Only the progress made in the Xbox One version matters.