Buyer's Guide: 2006-2008 Audi RS 4

Robert
By Robert Bowen
Jun 8, 2021 | Audi, Buyer's Guide, RS 4 | Posted in Buyer's Guides | From the Dec. 2013 issue | Never miss an article

Photograph Courtesy Audi

[Edito's Note: This article originally appeared in the December 2013 issue of Grassroots Motorsports.]

For two decades, the Audi A4 has comprised the bulk of the German automaker’s American sales. While the majority of those cars have been ordinary front- and all-wheel-drive sedans and wagons, for two short years the company offered a V8-powered variant that made a worthy alternative to the BMW M3: the Audi RS 4.

Hotter versions of the A4 were nothing new, however. A higher-powered S4 with a twin-turbo V6 under the hood was offered from 2000-’02. When Audi redesigned the A4 for 2005, the lineup included a V8-powered S4 as the performance alternative. The “uber A4” RS 4 appeared in 2007, initially available only as a four-door sedan to better match American tastes. 

Anatomy of an Audi

In the RS 4, the 32-valve V8 shared with the S4 was rated at 420 horsepower and 317 ft.-lbs. of tire-shredding torque thanks to different heads and cams, a new intake manifold, and more compression. The changes also included an 8000-rpm redline and 8250-rpm cutoff–pretty heady for an engine with a 92.8mm stroke. The only transmission offered was a slick-shifting Getrag six-speed manual. 

In place of the “ordinary” S4’s big brakes and big wheels were truly massive 14-inch front and 12-inch rear cast-iron rotors with aluminum hats. The eight-piston calipers came from another car in the Volkswagen Auto Group stable: the Lamborghini Gallardo. The 19x9-inch alloy wheels barely cleared the brakes. 

True brake-cooling ducts delivered air directly to the front stoppers. If all that braking power seems a bit extreme, don’t forget that the RS 4 was a nearly 4000-pound car fitted with a massive V8 engine. 

Suspension-wise, the RS 4 was basically an A4 with significantly higher spring rates; large, tubular anti-roll bars; and extensive aluminum links. The ride height was lower and the track was wider than on the lesser B7-chassis cars. 

The RS 4’s huge brakes, flares and lowered stance set it apart from lesser Audi sedans. The big V8 looks as beautiful as it sounds, though the cramped engine bay is not a place for novice mechanics. The RS 4’s interior is somber, but comfortable–an excellent place to gobble up the miles. Photography Credit: David S. Wallens

The most distinctive RS 4 suspension feature was Audi’s Dynamic Ride Control system. Each corner’s shock absorbers were diagonally linked through a central reservoir and valves that combatted the heavy car’s body movements. A combination of electronic and mechanical valves varied damping rates and preload to counteract unwanted suspension movement.

While the RS 4’s engine was mounted longitudinally–with all of it hanging ahead of the front axle centerline–the Quattro system was retuned to send 60 percent of the available torque to the rear wheels. This was an attempt to make the nose-heavy sedan handle more like a traditional rear-driver.

Big, Bold and Brooding

The RS 4’s exterior was just as brash as the big engine. Massive flares adorned the quarter panels, and the front fenders were formed in aluminum. A large opening in the front bumper fed the auxiliary radiators, while equally huge chrome exhaust tips protruded from under the rear bumper. 

According to Audi, of the visible body panels, only the front door skins and roof panel were shared with ordinary A4 sedans. Slightly different trim around the grille and windows further set the RS 4 apart.

The rarest RS 4 is the cabriolet, of which less than 200 were imported. Photograph Courtesy Audi

Inside, the super-sedan was all business. Typical of German cars in general and Audis in particular, the trim was dark and muted. It shared most of the interior with lesser S4s, although the RS 4 had distinctive carbon-fiber bits along with the requisite RS 4 logos and snug sports seats. In other markets the S4 came with a flashy, flat-bottomed steering wheel and thinly padded race replica seats; neither feature made it onto the U.S.-market car. 

Cheers and Jeers

As the ultimate B7-chassis Audi–and perhaps one of the best sedans ever created by the manufacturer–the RS 4 excelled. Reviewers gushed about the insane performance as well as the sweet V8 engine’s bottomless torque, instantaneous throttle response and beautiful soundtrack. 

That soundtrack could be enhanced on command, in fact, by pressing the “S mode” button found on the dash. This slightly gimmicky mode modified throttle response and fuel-injection mapping while opening flaps found inside the mufflers to change the exhaust note. In a promotional video for the RS 4, Jacky Ickx perfectly replicated the car’s exhaust note for the camera.


This was a truly fast car on par with the best in the world, including direct competitors like the M3. Instead of harping on the sedan’s portly curb weight, reviews of the RS 4 praised the excellent way that Audi managed to control it. 

Nearly everyone agreed that it was a true driver’s car and among the fastest sedans in the world, but it wasn’t completely without flaws. The price differential between the RS 4 and S4 was nearly 40 percent–an S4 started at $47,500, while a comparably equipped RS 4 started at $66,000. Plus, both cars required buyers to lay down an additional $1200-to-$2200 gas-guzzler tax.

Which brings us to the second downside of the RS 4: poor fuel economy. We aren’t ones to criticize a car for its gas mileage when it can do zero to 60 in about 4.5 seconds, but it’s hard to overlook a sticker that says 14/21 mpg–that’s similar to what you’d see on a full-sized SUV of the same year. Most reviewers seemed to agree.

The fuel economy hasn’t improved over time, but these RS 4 sedans will go down as one of the coolest Audis ever produced–razor-sharp looks matched with bleeding-edge performance. The biggest trick today may be finding one.

Things to Know

The RS 4 was designed as an exclusive, expensive performance sedan, with a style and presence unmatched even today. But that doesn’t make it immune to depreciation. Today’s prices have dropped to about a third of that $70,000 original sticker.

The hardest part of buying an RS 4 is finding one. Only 1455 sedans were imported for 2007, with another 355 coming the following year.  The 171 cabriolets are even rarer. 

But they are out there, and they can be a performance bargain if you shop carefully. Book values for 2007s with higher mileage have dropped below $30,000, with a few being advertised in the $25,000 range. The 2008 models are advertised for a few thousand more, while the rare cabriolets have asking prices (and selling prices) nearer to $40,000.

Since there were no changes between the two model years, try to find an earlier car in good shape to save the extra money for inevitable maintenance down the road. And when you do find one, don’t be too picky about the options and color choices; thanks to the Audi Exclusive program, cars could be delivered with nearly any combination of upgrades, interior options and exterior colors. Unfortunately, most were shipped with the DVD navigation system, which was slow and dated even when new.

The RS 4 is a high-performance car, and when new it was double or triple the price of similar sedans like the Mitsubishi Lancer Evolution and Subaru WRX STI. That means most examples haven’t fallen into the hands of abusive third or fourth owners, and you can expect their condition to reflect this.

Photograph Courtesy Audi

Engine and Drivetrain

Stephen Klitzsch at GMP Performance says that when it comes to $70,000 cars like the RS 4, the first and often second owners will service them at the dealership. It’s when you get to the price they’re at now that do-it-yourselfers start to tinker with them and post photos on message boards asking for help. 

Be wary of these kinds of sellers, especially if they say the car needs minor work or that a check-engine light is no big deal. “Bang for the buck, they’re awesome cars,” Klitzsch explains, “but as they get older, the maintenance will get you. To replace the oxygen sensor on the right-rear bank is 6.8 hours. So you’re looking at $875, including the $250 sensor.”

“An exhaust upgrade is great because the engine just sounds incredible,” Klitzsch says. “The exhaust isn’t worth much power–like 5 to 10–so it’s merely for the musical enjoyment.” He claims a supercharger will add 100 horses at the wheels.

The FSI direct-injection engine is generally very reliable. The same engine is used (in detuned form) in the S4 and Q7, and it has proved to be robust in those vehicles. 

Some owners have reported problems with carbon buildup in the intake tract, including the backs of the intake valves. The result is decreased engine performance and, if the carbon gets bad enough, a check-engine light. The carbon can be removed, but it requires disassembly of the top half of the engine. Chemical cleaning methods appear to be less effective.

Chassis

The issues that crop up most frequently in any discussion of the RS 4 involve the suspension. The complicated cross-linked DRC system can be the source of frequent clunking, squeaking and general suspension weirdness. By now, most cars have had the suspension overhauled–sometimes multiple times–by an Audi dealer under a service campaign. 

Klitzsch told us, “The upper control-arm bushings can wear out pretty quickly. The bushing breaks inside it, and it starts making clunking sounds. A factory arm is $160 apiece. There are replacement kits all over the place. We do an upgrade–$500 for the set of four upper arms–and it allows you to adjust caster, which helps with turn-in. The upper arms are what usually fail.

“The nice thing about ours is that you can adjust them without having to take the ends off,” Klitzsch says of GMP Performance’s upper-arm kit. “With others, you have to remove the spherical end and turn it, which is a real pain on the alignment rack.”

If the factory suspension has failed, it’s typically less expensive and more reliable to simply swap to an aftermarket coil-over system than try to get it working properly.

Assuming the car you find is in good condition with thorough service records, the only thing to worry about is the high cost of brake pads and tires. The nearly 4000-pound car eats front tires for lunch, and its 255/40ZR18 or 255/35 ZR19 tires are not inexpensive to replace. 

Brake pads aren’t particularly expensive from the aftermarket, and they’re easy to change. The bimetallic rotors are pricey ($400 each) but should last through many brake pad changes. 

Body and Interior

While the RS 4 is generally a reliable car, all recent Audi models seem to suffer from an exceptional level of complexity that makes working on them more difficult for the DIYer. A total of three radiators, brake ducting, HID lighting and countless subassemblies crowd the front of the chassis. 

Audi’s own service manuals require removing the grille/bumper cover, radiator, radiator support and headlights to do many jobs on the front of the engine. The so-called service position makes access much easier than it would be with the parts in place.

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