Here is the content of the Forza Horizon December IGN Car Pack. Coming December 4th, 2012 for 400MSP to the Xbox Live Marketplace featuring 7 new cars for you to collect and cusomize.
Season Pass owners can download it for free from the ingame Marketplace.
December IGN Car Pack
1971 AMC Javelin AMX (FREE Download)
2008 Aston Martin DBS
2012 Ferrari F12berlinetta
2011 Ford F-150 SVT Raptor "Halo Edition" (FREE download)
2006 Ford GTX1
2006 HUMMER H1 Alpha Open Top
1993 McLaren F1