Interesting. I have an '06 C4 with 6 speed and have never smelled anything. I've only got about 10k miles. I do notice a difference in the transmission compared to my BMW coupe with 5 speed. The Porsche manual specifically advises against lugging the engine, that is poking along at too low RPMs after first gear. My P car is very sensitive to that, if I get lazy or distracted and let the RPMs drop there will be some shudder in the transmission/clutch. In the BMW, I can go let the RPMs drop lower in any gear and there's hardly any transmission/clutch noise.