B7 S4 after 8 Months ownership - Got Mine in January
Ive done 8500 Miles since January and so far only had to replace the tyres and Aux Belt. touch wood have not had any horrible issues with her although perhaps some slightly excessive oil consumption on spirited riving but this isn't to be unexpected I guess.
Those chains ... terrify me haha. Usual 1-2 second rattling on startup most of the time which is apparently normal but I still dread hearing it. Those chain snapping horror stories do that to you! And the injectors are fairly noisy. As above I have not heard from my garage of anyone having gone in with cam chain issues. although I think Audis claim at 300k being average chain and guide wear and tear is bull! If they go they go that's all that can be said unless you are in the fortunate place to just get them replaced which is not cheap at all even at an indi...if they dare take the job on, a lot refuse!
Best MPG I have hit is 29 and lowest is 6. Average around town 17.
Regular oil changes with Fuchs 5W40 (I use) every 9k and Shell V power Nitro always.
One thing to watch out for is tyre pressures on the front causing uneven excessive tyre wear due to the engine weight.
Coming from a remapped 2.0T special edition personally didn't find it excessively powerful in comparison but obviously it is more powerful overall. When test driving make sure you open it up properly and hit the full rev range as Ive found above 5.5k rpm she does go for it.
At 5k + a second actuator kicks in and this is definitely something to check under the bonnet when buying as this is visible infron of the engine bay and if it doesn't kick in then you will be way down on power.
Overall I love the car, the sound still makes me smile even though still stock and fuel usage I am used to now so doesn't really bother me.
and Quattro is amazing it takes off like a rocket in anything, does what it says on the tin. Don't regret the purchase one bit. And the 155 limiter works perfectly
Im sure theres more info I can give you if you want anything specific just ask