
This essentially gives players of the older games some additional cars to add to their in-game lineup of rides. There are five cars in total and they're broken down by tiers.
The rewards are cumulative, so that means Tier 6 will get everything from the previous tiers as well. To get these cars, you had to play and do specific things in the previous games starting with Forza Motorsport 2 on the Xbox 360.
If you are a loyal fan of the game, you should be able to earn all of the cars without any trouble at all. You will be notified of the level you earned and the cars you've unlocked upon logging in to Forza Horizon 2.