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Join Date: Oct 2009
Location: Marietta, GA
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The only major problem with the RS6 is the Dynamic Ride Control system (DRC). The OEM supplier to Audi, Boge had a faulty strut design with an inner seal that would fail under pressure (16psi is what the system is supposed to be) and the series of (2) struts would fail. We called it the "Trunk Monkey" since you would hear the rear strut clunking in the back. Audi finally fessed up (under threat of a class action law suit from an RS6 owner who was also a lawyer) and had Boge redesign the strut for both the RS6 and RS4s. They started the recall campaign in June of this year and replacements for all (4) struts and (2) accumulators in August of this year. It is/was a real sore subject with RS4 and RS6 owners. The terrible thing is that they used a reworked Gen III DRC system in the new C6 RS6 even though the RS4 had a Gen II DRC that was supposed to be more reliable than the Gen I RS6 DRC system. The RS4 DRC system is failing twice as fast as the RS6 setup.
Other than that, the RS6 is a rock-solid car. I've owned two of them. I consistently got 18MPG around town and 22MPG on the fwy since the car runs as a V8 when you don't have your foot in it. The exhaust note (with the OEM optional SE setup) was pure sex on startup and at WOT. The fuel tank was rather large for good range.... usually 340 miles on a tank for FWY driving and 300ish for around town. The "surge" of twin turbos is very insanely addictive.
I'm not super thilled with the M5's 12MPG around town and the small fuel tank. The "tinny" exhaust note at cold start up is also weak to the point of pushing me to replace it very soon. I'm almost embarrased to start my M5. Sounds like a diesel until it warms up. The price of having a V-10 I guess. Luckily this is just my hobby car. I take my 2009 Maxima with 27MPG for long business trips.
Being a 2003, the RS6's electronics and interior are dated and so now is the exterior. I had a REVO user-selectable ECU tune that took the car from 450HP to 505 (mild) 517 (medium) or 525 (full boost, timing, fuel etc.) Stock, both ran a 12.8 at the 1/4 mile track. Tuned there are guys running low 11's. The weak point is the torque converter-based transmission. It is really easy to get 600HP from the Cosworth engine without any issues but the tranny can't handle it. Most of the hard core guys send their tranny off to various companies get it hardened to handle the extra power from engine upgrades, etc. There are a few MTM 700HP C5 RS6s out there. The new C6 RS6 is a twin turbo V-10 @ 580HP (way underrated). Tuners and owners are getting 650-700HP easily (as per this video clip).
When the F10 M5 comes out with the twin turbo V8 there will be a whole new world of modifications available to M5 owners with this platform. Huge HP mods will be available with simple ECU tuning and bolt-ons. It will be a wild ride. The 2011 C7 RS6 is going back to a twin turbo V8 just like the F10 M5 to get better fuel economy. I think this is a smart move by Audi and BMW. I was shocked at the relatively good gas mileage of my TT-V8 in the C5 RS6.
Last edited by Copper; 3rd November 2009 at 11:45 PM.