If this is the single car DLCs they are always free. They are samples of the full packs you can buy for stupid amounts of money. I'm either going to wait till all the packs go on sale or snag the Platinum Hits edition to get them. I have the CE still sitting sealed in my backlog since I never finished Forza 3. Do they actually send out the "VIP" cars? I never got any from them for Forza 3 and they ignored my emails. :(
The Facebook givaway car may be unique so I'll give them a like for it.