Because the game was published by Codemasters and featured licensed music and potentially vehicle designs, it was removed from sale when those licenses expired.
Searching for a "free full version" download of is complex because the game has been delisted from all official digital stores (like Steam and Xbox Live) since roughly 2013-2014. This means you cannot buy it directly from primary digital retailers anymore. Status and Legal Availability FUEL (2009) Game Download Free Full Version
Even if you find a way to download the game, running it on modern Windows (10 or 11) requires several community fixes due to outdated security: How to Install Fuel (2009) On The Steamdeck/Linux Because the game was published by Codemasters and