This is unique to Forza Motorsport 4 . The DLC itself is a small "key" file (often 100kb). The actual car data was included in the large Title Updates. If you have the DLC file but not TU10, the cars will appear in the Autoshow as "Locked."

The solution? Downloading your Forza Motorsport 4 DLC directly to a USB drive. Here’s how to do it safely and effectively.

Forza Motorsport 4 (FM4) DLC Acquisition and USB Installation Report As of , Forza Motorsport 4 (FM4)