Evolution is a hell of a thing. In science, it means that an organism has become better suited to its environment. In automotive technology, it’s often represented as vehicles being altered to adhere better to changing safety and fuel economy regulations.
Sometimes, though, it happens when there is a lack of regulations. Like sporty German sedans that are designed to eat up miles at high speed on their home country’s de-restricted stretches of autobahn, and look understatedly cool doing it. There have been a bunch of extra-freaking-cool examples of German stealth sedans over the years, but one in particular that’s often overlooked is among the best: The C5-generation Audi RS 6, which was sold in the USA for just the 2003 model year.
Here’s what makes this mighty full-size sedan a rare legend, as well as something to be careful with if you ever consider picking one up for yourself. 
Audi
Big on Everything
After years of American enthusiasts craving a proper Audi RS model, the C5 RS 6 was the first to be sold in our nation’s dealer showrooms. Slightly lesser S models were great and all—says the B5-generation S4 owner—but we never got anything from the four-ringed brand offering the pinnacle of performance, the widest wheel arches, and a handful of satin metallic exterior accouterments to show it all off.
Considering the RS 6’s epic stats for its era, I ain’t mad. Under its hood is a 90-degree Cosworth-built 4.2-liter V8 sporting twin turbos and a forged steel crankshaft. Power output is rated at 450 horsepower and 415 pound-feet of torque. A five-speed ZF automatic transmission was the only option for sending all this power to its Quattro all-wheel drive system, which Audi says is due to it being the only unit that could take all that power.
The C5 was heavy for its era at 4,229 pounds, but with 450 horsepower on tap, a mid-four-second 0-60 run is quite possible, and 0-100 happens in just over 10. Luckily, its brakes are up to snuff: eight-piston calipers clamp down on 14.4-inch rotors up front, whereas a big single-piston unit grabs a hold of 13.2 inches out back.
Outside of big stats, it’s a generally big sedan for its era, too, sporting wider wheel arches than the standard A6, bigger front bumper inlets to feed its intercoolers and aid cooling, plus an overall sportier body kit.
Car and Driver named it the winner in a comparison with the BMW M5, Jaguar S-Type R, and Mercedes-Benz E55 AMG.
“Flat cornering, plus Super Glue adhesion, plus beautifully weighted steering, plus abundant power, plus monster brakes—the front calipers grip with eight pistons—make the RS 6 a supremely composed performer at high speeds,” the late Tony Swan wrote. “It inspires confidence that goes beyond its rivals’—an endearing trait in a car in this performance category.”
High praise, and sadly, Audi only sold 1,435 of them in the USA. That means it’s good-looking, potent, and rare—a recipe for enthusiast success for sure.
Surprisingly Inexpensive For Its Rarity
If you’re a blue-sky-thinking, curious early 2000s car connoisseur like yours truly, the next step after going through these stats and impressions is taking a gander at Craigslist, Facebook Marketplace, and every other fine (and not-so-fine) method of hosting used car for sale ads.
It can be tough to find examples in general, though, due to the under-1,500-units-sold part. By comparison, nearly 10,000 E39 M5s were sold in the USA over its four-year run. Its tough finding W211 E55 AMG production numbers, but it looks like just under 8,000 were produced worldwide.
C5 RS 6s can be surprisingly cheap. A quick perusal of Classic.com reveals an average sale price of $18,463—OK, that’s not exactly cheap—but the lowest sale is just $7,600. That’s more my speed, though, there could be some sketchiness at that level. But why the massive spread?
One word: Audi. Well, actually, maybe two: Audi complexity. Don’t get me wrong, I’m always up for a challenge, especially after being conditioned for complexity with my S4. But there are things about the mighty RS 6 that could be a real buzzkill.
But Here’s What Makes It a Legend in Other Ways
There’s a lot going on behind the C5 RS 6’s front bumper, and it all requires attentive maintenance. The thing may be a big full-size sedan, but all that under-hood space is occupied by a biggish V8 with two turbos hanging off each side. It’s time-consuming to perform jobs that are otherwise much quicker on other platforms. By the way, servicing or replacing either or both turbos is an engine-out job. Then there’s its timing belt service, which is a measly 35,000 miles or three years, whichever comes first. And it’s a good idea to do a bunch of stuff while you’re in there, like various tensioners and the water pump.
The transmissions are infamously weak as well, apparently, they could barely take all that power from the factory. Dedicated enthusiasts have thrown in upgraded components or swapped to six-speed manual units with a sturdy clutch and flywheel combo. Otherwise, regular fluid changes are a must.
Then, more general servicing quickly gets pricy: The engine takes nine liters of full-synthetic oil. Though, the German parts tax doesn’t seem as bad as it used to be with a bunch of retailers in the game these days. Old cars mean old rubber, and old turbocharged German engines have a mess of rubber vacuum lines under their hoods that are often the source of random issues.
The RS 6 sports hydraulically actuated suspension that reduces body roll in the twisties, too. I’m shuddering at the thought of having to troubleshoot that, but luckily there are plenty of aftermarket coilover options that do away with it and avoid any potential headaches entirely. Finally, who can forget the many, many bushings tied up in the RS 6’s front double-wishbone and rear multi-link suspension?
Still, I’d Love to Own One, And I Bet Some of You Would, Too
Despite the C5 Audi RS 6’s ability to rob you blind, there are ways to potentially avoid it. Service history, any indication of attentive ownership, an open mind, finding the cleanest example one can for their money—all stuff that applies to keeping a cool and critical head about navigating the used car market in general, but it really helps here. Then, there’s expectations: If you’re salivating over a particularly cheap example, be ready for a world of pain (or a thorough lesson in DIY maintenance). A well-cared-for, higher-priced example might never cause any headaches at all … though, I’d hate to be too optimistic.
Like any enthusiast vehicle, I wouldn’t be afraid of miles if there was ample service history. Hell, if one’s got 170K or more and running well, there’s a good chance it’s been looked after, because it surely would’ve been mechanically totaled by then if it wasn’t.
The juice could definitely be worth the squeeze, and I’d love to find out someday. This muscular sedan looks great, it’s a total monster, and it comes from an era of German engineering that’s known for wonderfully solid and confident ride quality. It has the ability to rip down the highway at massive speeds in total comfort, and just oozes sense-of-occasion.
We can’t forget the aftermarket, either—apparently, over 500 horsepower is as easy as an ECU tune. Though, I’m not sure that’s the best idea considering its transmission situation.
I actually got to very briefly drive one while in high school in the mid-aughts. A friend’s dad owned one, and let her borrow it to come hang out one summer night. Knowing my buddy and I loved all-things VW and Audi, she threw me the key and let me take it for a spin. I’ll never forget pulling up to a long, empty, straight road and dumping the throttle; it was my first time experiencing something properly fast.
Makes me wonder if my career in automotive journalism has just been one long, drawn out quest of chasing that high. If I ever pick one up for myself, hopefully it’ll be less financially damaging than a high brought on by illicit drugs. Hopefully.
You’ll probably spend more in the first two years of maintenance than on the purchase price. But the interludes where it’s working it’ll be great, even the “regular” 4.2 v8 was a great engine, rev-happy, smooth, I can only imagine what this hot-rodded version is like. But I’ve had too much experience with mainstream A6 offerings to be tempted by a rare low production model. My mom is still somehow trucking along in an ’02 A6 2.7T and even with only 118K in that time it always seems to need something. And buddy’s experience with an Audi Allroad 2.7T that generation makes me laugh even more at the idea of these being a “deal.”
The C5 gen was the car I cut my german car teeth on. My pop’s had a 2.7tt 04 when I was a teen that he passed on to me and using my buds on audizine as reference I made that thing into an unreliable monster. But the RS6, oh the RS6 I always coveted. I very briefly had an O1E manual swapped S6 and it was glorious and I ALMOST pulled the trigger on an RS6 but they were still 25-35k and I went Focus RS instead at the time.
I love this car and don’t listen to audi, the O1E totally handles the power of this thing just fine (just ask audizine) and if I had a garage where I could keep more cars I’d import an RS6 Wagon and manual swap it.
As someone not afraid to wrench on his own Audi’s, what’s keeping me from this generation is a well maintained example will cost more than I want to spend, and a “meh” maintained example will end up costing more than a well maintained example to get tip-top again. I will settle for admiring the ones owned by people more fortunate than I.
I remember the first two of these I saw on the road when they were new.
Both were driven by women between the age of 55 and 70, in a very wealthy part of Massachusetts. The kind of place where the normal empty-nester car is a Mercedes-Benz E-Class wagon. Either way, both seemed like the case of the couple going to the Audi dealer, buying a new car for their wife, and them saying they wanted the best midsize sedan they had and wouldn’t consider anything but.
They were probably meticulously serviced for the first 3 to 5 years, but mostly putt around town to brunches, get coffee, do groceries, etc.
I think I’ve seen one (not the same ones, in general) recently, but they’re unicorns now.
I tend to be too optimistic about my care and dismissive about how others keep up their cars. I’m working on toning down this response and being more sympathetic and realistic, and become a better person in the process.
When I read about the German sub-supercars, this is a good chance to practice that skill. There really are bad designs, fragile parts, underspecced components and systems, hubristic “non-service part” designations. I covet the Ms and AMGs and RSs, but I’d have to have far more money than I have. I already have more money than sense and I have very little money.
Those two paragraphs about repair and maintenance were enough for me. Nope! I’d say you’re better off with a meth habit than one of these.
This car is amazing no doubt, but I know from personal experience that this entire generation of Audis, mechanically, was designed to empty your wallet and break your heart.
Yeah looks and sounds great…but the concerns are too large to want to actually own one of these.
it’s best to own one of these when you’re in your 20s and have no money. why? because it forces you to learn how to work on a car because fixing it at a specialist is simply too expensive. I’m gonna force my future kids to do the same as I did if they turn out to be car nerds like myself haha.
I enjoy appreciating Audis from afar, but like with most German machines the complexity tends to keep me away from ownership. But for whatever reason Volvos don’t bother me…
No thanks. I saw that episode of Wheeler Dealers lol
Used to work at an Audi dealership back in 2014 and indeed the S and RS(RennSport-literally “Racing Sport”) were special beasts! We had quite a few special orders for top end Audis. RS 5, S6 RS 6,you name it. We had an RS 7 come of the transport truck one time and all you heard after the PDI(pre delivery inspection) was someone trying to drive to snot of it (and the cooling fan working overtime to bring the temperature on the twin-turbo V8 down!)LMAO
My preferred weapon of choice-the S5 coupe with the 6-speed manual transmission. but you had to scrutinize those because whenever one showed up on the used car market, they would be driven hard and put away wet. A lot of them were rebuilt after wrecks. Same with the S4 models.
I have one in my garage right now with 22k miles. 🙂
Not much milage for the age, gotta drive that thing more so things can keep lubed up!
Any issues? Favorite feature? Tell us a little more
I have been sinfully neglectful. I’ll write more about it one day, but it mostly boils down to what happens when you have a special needs kid and that overtakes every single aspect of your entire life for sixteen years running, to date.
Center differential leak. That is what waylaid mine. So many favorite things. It really was/is a special car.
did it spend that much time in the shop, or did you not drive it because you were afraid of it going in the shop?
i never realized they were sold in such a low number. I could have sworn i have seen quite a few of them in my valet days.
Having owned a few C5 A6 cars over the years, both 2.7T and plain ol’ 2.8 flavors, the one I always wanted was the S6 Avant, ideally with a six-speed manual swap.
I had one, with automatic. I regret selling it very, very, very much. Although, saying that, I did trade it for the RS6 so WTF am I taking about?
I had one with the O1E! Bought it off another audizine dude and drove it 700 miles home
It was awesome but man I wanted that RS6
You’re really spoiling us with these weekend articles, Peter. The C5 A6 has a very special place in my heart because my uncle, who unfortunately passed in 2016, had a 2.7T C5 that he chipped. I was pretty young at the time, so I’m not sure how much power it made, but I LOVED riding around in it because he’d put it in manual mode and let me shift from the passenger seat.
However, I still have vivid memories of him taking me and two of my cousins out in it on Christmas night in…maybe 2002? 2003? He asked us if we wanted to come out for some driving and of course we all lined up. He wound up taking us to this ridiculously long, secluded on ramp in North Jersey and more or less saying “hold my beer”.
Anyway, he floored it and it was like nothing I’d ever felt. He started calling out the speed…and while I wouldn’t necessarily trust the memory of adolescent Nsane, I recall us getting up to 150 before he slowed us down. As a kid and budding car enthusiast it was just the coolest shit I’d ever experienced and I bragged about it for years to anyone who’d listen.
Was it the safest thing in the world to do? Absolutely not, but as you might imagine the roads were absolutely deserted because it was Christmas night and he had a very specific place he took us. We all need a cool uncle to show us the finer things in life sometimes…and between my uncle who tuned German luxury cars and my uncle who dragged a Dodge Dart, I was in good hands.
Rest in peace Doug. I still think about you when I mash the throttle on on ramps…and fortunately his sons are doing well, growing up shockingly fast, and are a big part in our lives. I routinely throw the keys of my cars to them with a smile and a wink at family gatherings. I kind of feel like I’m paying it forward, even though I should absolutely not be trusting a college student and his teenage brother with my machines.
Ah man. Core memory unlocked. Very cool. ANYWAY…as you might imagine these have always been on my radar for obvious reasons. I like to call the 2000s the German sport sedan anarchy era. They truly went balls to wall with this stuff and we didn’t know how good we had it back then. These days BMW, Audi, and Mercedes are more or less shoving gratuitous amounts of tech into their cars and focusing their performance models solely on numbers and being easy to use.
It’s a shame, because I’m one of those whackos who thinks your car should scare you a bit and require skill to drive fast. I’m not really interested in some super sedan than can hit 60 in 3.3 seconds every single time at the push of a button. That being said the real question is this…would you rather have the C5 RS6 or the C6 S6?
This car is special…but the C6 S6 has a V10 that’s more or less a more civilized version of the Gallardo’s. I’m sure they’re both similarly nightmarish to keep running, and I can’t help but feel like MOAR CYLINDERS is always the answer.
V10 heavy. 🙁
But V10 go brrrrrr
Agreed, sounds amazing, but better from behind the seat than in front of it. That was all I was saying. R8 yes, S8 no.
Sorry about your uncle. I love this memory!
Thanks! I do too. He was super influential throughout my journey to becoming an enthusiast. I honestly hadn’t even thought about that night in probably 10 years but reading about C5 A6s brought it all flooding back.
Sorry to hear about your uncle, that’s really rad!
C5 RS6 Avant from some meticulous german in 2028 tbh
and of course an O1E manual swap (don’t listen to audi, plenty of dudes have swapped em)
I had a 2003 A6 allroad and loved every minute of it. However, when I swapped out the air suspension with coilovers, the ride was never the same. In the article you reference how great the ride is with the hydraulics in place. I have no doubt that that is true. Might be worth a little troubleshooting before you swap them out.
That’s been my general experience with replacing air suspensions with non-air suspensions across all manufacturers – the ride suffers dramatically.