Those pitlane penalties are brutal! And if you are overly careful at the entry (which you probably are) you get an extra risk of getting smashed from behind as well.
I did 2 races now in the GT-R, after
@BBerlingo posted about it earlier.
Race 1: Mixed DR C / DR B lobby, as a low DR B driver myself. Started 11th. I had absolutely no race pace, but I did keep it on track whereas a lot of others were spinning out. Pitted after 7 laps for softs, and tried to haul in P1 and P2 who started on softs but were now on the hards. But the gap was too big, so I finished P3. Not bad from P11.
Race 2: Suddenly a mixed DR A / DR B lobby where I started all the way back from P16. Again my race pace wasn't very consistent, but I did manage to keep out of trouble. Wanted to pit again for softs on lap 7, but I crossed the outer pit entry line so I continued for one more lap. Came out in P8 after the pitstop, not bad with many DR A drivers in the lobby. I overtook one poor soul who for some reason started on hards and after 4 laps put on the softs, so his tyres were dead. P16 to P7 => I'll take that! Despite running 3 seconds slower than my quali lap.
I prefer the GT-R above the BMW. You always have to be a little careful of course, but even on worn hard tyres I felt sure of my corner exits in T7 and T9. In most laps I saw myself pulling away from or closing in on my competitors at the T7 exit. Quite the opposite from what I experienced with the BMW. Many people are racing it because it simply is the meta, but it can be a fickle car, depending on your driving style.