Depends on the track. If it's a track you've downloaded, you can go to the GameData\Locations\<Track> folder and edit the GDB file. Just change the 'Category' value to whatever you want.
However, you should be aware that changing that file can cause problems online. I kept getting booted as a 'possible cheat' from an RD event because I had used a tool to sort my tracks into alphabetical order. (It modifies the GDB file to accomplish that.)
Now I think I'm going to create other categories but I don't know how many I can create without display problems (screen is not wide enough for a lot of categories...).
Is there a say to modify encrypted GDB files ?
Ok, I didn't know if it was working with GDB files too. Thanks !Hey, Samu15, look here:
http://www.racedepartment.com/race-mods/49725-modelid-classid.html#post753691