I agree. The best way to get real lap times is to work with the MD file.
Tha default palyer's grip is 16384: the only way to change it is the Belini Grip patch, that allows you to use the value of the driver you choose. For what i know at the moment, that value is not simply the performance of the CC driver, but a sort of mix between the driver and the car performance (except the engine power (bhp in Gp3edit), the reliability and the ability range that are set in different boxes).
But the MD file is the best way to have good lap time. The main value you have to set are:
- cc grip factor (the grip)
- cc power factor (the engine power)
- track grip
- air resistance (better: air efficency)
- ride hight
- cc setup (gears and wings)
- timing factor (very important)
- timing factor fine tune (very important too)
Roberto Scandura has made a very good Tutorial for the MD, you can download it from his site.
Working only with Gp3edit is limiting and the result could be: races very easy to win, and races quite impossible not to be lapped, expecially if the MD is not very well set (and others little problems such as CC crashing enterin/leaving the pits, not reaching the right top speed, running out of fuel in the last lap of a race, having a bed pitstop strategy, or a bed tyre consumption for you...).
Hope this can help you.
Bye, Claudio.