It's there: http://www.giantbomb.com/guides/forza-motorsport-3-level-1-50-gift-cars/1421/

@theArgyleMurder: I've put that up as well. Look at the Guides page and you'll see the ones that list which cars you get at which levels.

Not a problem. It definitely made it easier for me.

I posted this as a comment on the achievement page...  For this achievement, as it says, you need to own at least one vehicle from EVERY manufacturer. Here's a list of what you Win, and what you need to Buy in order to get this achievement.Acura -  Win - Acura #66 de Ferran Motorsports ARX-02aAlfa Romeo -  Win - Alfa Romeo Brera Italia IndependentAston Martin -  Win - Aston Martin #007 Aston Martin Racing DBR9Audi -  ...

For this achievement, as it says, you need to own at least one vehicle from EVERY manufacturer. Here's a list of what you Win, and what you need to Buy in order to get this achievement.Acura -  Win - Acura #66 de Ferran Motorsports ARX-02aAlfa Romeo -  Win - Alfa Romeo Brera Italia IndependentAston Martin -  Win - Aston Martin #007 Aston Martin Racing DBR9Audi -  Win - Audi R8 5.2 FSI QuattroBentley -  Buy - ...