Ultimately, while the BMW M3 GTR isn't supposed to be used in Need for Speed: Carbon 's career mode, the dedicated modding community has made it entirely possible. While the process requires some technical effort, using a Save Editor to fix the CD-key checksum is the most direct method for existing saves.
What you are playing on (PC, Xbox 360, or PS2/PS3)? nfs carbon bmw m3 gtr in career save game
If you force-add the BMW M3 GTR into a vanilla career save game, the game will erase the vehicle the moment you visit a safehouse. This happens because the engine continuously verifies if your active car matches the legal unlock flags of career mode. Ultimately, while the BMW M3 GTR isn't supposed