I don't think that it has been implemented yet as in the GPxPatch there is an option to use a setup file (text) that enables you to set different levels of performance according to the the setting you give it -for each team and driver in qualify and race conditions. This is enabled with the "set car power team dependent" on the GPxPATCH (and of course select the file from the program).
For more info I would suggest going through the GPxPatch documentation. You could also download the performance pack from Acciari-Schroeder, which is really awesome
that contains files like that and is well-documented (follow the instructions carefully). You can find it on this site.
My lap times have significantly imrpoved (from 1:48.xx in Spa I can do now 1:45:xxx which gives me P2) and no brake lockups with keyboard!!! Serious playtime hehe!!!
-=Johnious=-
..You can't easily win a race from the first corner... You can sure as hell lose one though...