I leave a mod GT4 Toyota Celica for our Dirt Rally. To operate must replace the files for the auto Lancia Delta Integral (LDI). You only need to copy the "cars" folder inside where they installed the game. Within the archive is the backup of the original LDI to return whenever they want.
The setup is based on the Lancia Delta Integral, even I could not edit the ".CTF" files are those which are settings of each car. GREETINGS FROM ARGENTINA
Installation: Copy Folder cars to "Dirt Rally> cars
Below different videos in different Test: