Do this:
1. Open your cars.wad using GP4Master
2. In CARS folder, look for car_sauber_car1_lod_0.gp4
3. Make a copy of that file and rename it to car_sauber_car1_lod_
1.gp4 (overwrite the older one)
4. Recompile the cars.wad again
And that¡s it, the problem is that Viper's Sauber has the lod1 of the first car which belonges to the Renault car, that's why you see the Renault sometimes
I wish this helps you
I'm against sigpics