Bolded part. This is a really big depends. If you talk about BMW M car, or MB AMG, or even Audi RS, then yes, you are correct.
On the other hand, Audi A/S(4,5,6) cars are fairly tame. They are, at the heart, re-engineered VWs with nicer stuff. Parts are middle of the road expensive and just about anyone can work on them. I used to own an 2.7TT S4(though not very long) and didn't find it to be problematic. BUT, they are not that good of a handlers. Better than most, but not on par with Infinity or most BMWs. OTOH, my E39 M5 constantly needed something.. sometimes it's small, sometimes it's big. Still, my most favorite car and I didn't think it was unreliable because it was as reliable as I expected it to be.
Most new cars suffer from being overcomplicated and having all this new technology crammed into them, some fairly untested. Drivetrains are pretty reliable.. Although anything with turbos needs special attention to last and probably extra maint for when those turbos will need replacement.
From your list, G37 would be my choice if you want a reliable *sport*(handling) sedan that is fairly quick and has MT. I'd owned a G35C back in mid 2000s and still think it was one of the best handling cars that has a rear seat. Better than most M3s in my view.