So within the next year or so, I'm thinking of buying a "nicer" car, and I've got a couple in mind. I'm partial to G35's (more on that a bit later), but I've also been a long-time VW fan and have owned several, thus by extension I like Audi's too.
So, regarding the G35: I had an '06 sedan, 6mt, sport package, aero package etc. I loved it. Some people say they are unrefined compared to the german competition, but maybe that's why I love them. They have a very direct mechanical feel and sound, and I really like the VQ 35. They have a fairly large aftermarket, they're well made and seem to hold value fairly well. I know about the weak-ish clutch, and possible oil consumption issues with the "rev-up" version of the VQ.
This time around, I'd buy a coupe, as I don't NEED a 4 door. Again, it would be a 6 speed. The coupe's are dead sexy IMO. Looks like right now a very nice '05-06 can be had for around $15-$18k.
Now the Audi. I'd be looking for an '04 or newer 4.2 V8 S4 with the manual box. Prices are pretty amazing given that these were like $60-70k new (Canada). I know about Audi electronic etc issues. Is there anything other than that to be overly scared of these cars? I've never driven one, I assume they would be quieter and smoother than the Infiniti? Maybe at the cost of some fun though. Heavier, and all wheel drive, that's a plus and a minus. Price is maybe a bit more than the Infiniti, but not much.
This car will be used for summer cruising, maybe the odd road-trip with the missus, mostly just a nice toy. MAYBE a couple autocrosses per season. I've got my Jetta for more regular abuse of that sort. The car will not be a project. I'd keep it stock maybe with the exception of a nice sounding exhaust. What are your opinions?

