Just saw this apparently Microsoft has announced the Forza 5 car pass which includes dozens of cars (Neogaf said 40) for 50$ which is kind of a step price if you ask me. But hey at least you will save a whole of 18% if you buy the pass.
Here is the link for the officia Xboxl site:
That is like a full retail game for just cars. I just hope this does not become any kind of trend because that is really expensive.