I used to have that game on mac but I don't have it anymore.
Anyways, open the folder that contains the app and right-click on it.
2. Click on show package contents
3. Open the folders Contents > Resources > transgaming > c_drive > Documents and Settings > All Users > Application Data > NFSU2
Not really sure on the exact location but it should be something like that. If it is not there, check in the Documents folder of your mac where a folder is named My Games.