Firstly, what an interesting combination of tracks and cars you've put together
I started with the GTR on Matterhorn, which was tremendous fun, except for the tank slappers in the fast downhill section, which kept catching me out at the limit. There's some painfully slow and tight sections for such a powerful and wide motor, and the management of the mass of the GTR was quite tricky.
Next up the Tesla on Spa. Very eerie going round in near total silence but very rewarding to get it just right. The Tesla is a bit slow on the straights and you need to do the tiniest little steering adjustments in the bends to keep it on the tightrope between grip and the grass. It's a very strange car that loves to understeer in and mid corner, then just as you think you're getting away, it oversteers like mad. My favorite combo this one.
RBR in the Focus wasn't much fun for me, the understeer on the downhill, heavy braking, sharp bends was appalling. This, though not enjoyable, made it very taxing to get right. I don't know if I'm talking out of school here but the track limits on corners 1 & 2 and the last two are very forgiving. i.e. You can cut the hell out of the first two and go super wide on the last two without the lap being ruled invalid by the computer.
Times
RBR 1:50.331 (TCS 1, ABS 1.)
Spa 2:51.083 (TCS 3, ABS 1.)
Matterhorn 1:45.690 (TCS 1, ABS 1.)
Completely stock cars, as they come from the dealer. Manual transmission. No oil, no washing! I did about 15 laps of each to gather those times.