Forza Horizon's 1,000 Club DLC pack will be released for the game on April 16, i.e tomorrow.
The free pack includes the Ford F100 1956 and the RUF CTR2 1995 as well as new challenges for every car in Forza Horizon. Some of these trials focus on speed, other focus on driving skills and stunt abilities.
Apparently, those with the new pack installed will see the game recommend challenges for them based on the cars in their garage.
In all, the new pack includes 1,000 new challenges, 10 Achievements, and two new cars. Even better, it's free.