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Originally published by www.AudiWorld.com on November 20, 2005

Link to original article

Link to more pictures

RS4 engine revving video

RS4 full throttle acceleration video #1

RS4 full throttle acceleration video #2

RS4 full throttle acceleration video #3

Twenty-five point seven meters per second. This number kept bouncing around in my head as I playfully blipped the throttle of Audi’s new B7 RS 4. Twenty-five point seven meters per second is precisely the average speed of the RS 4’s 8 pistons as it’s humming along at a stratospheric 8250 RPM. That’s faster than any offering from BMW, Porsche, Ferrari, or Honda. In fact, no other production car has a higher mean piston speed. It even matches the world champion 19,000 RPM Renault RS25 F1 in terms of reciprocating velocity. This engine is no joke and exists solely to prove Audi can build a naturally aspirated engine among the world’s best.

It all started on a sunny Saturday afternoon at Germany’s Hockenheimring during Audi and quattro GmbH’s RS Driver’s Challenge. This world class event is held for owners of Audi’s RS cars to improve driving skills and car control within the confined environment of a Grand Prix racetrack. An RS owner in spirit (but not in reality), I was at Hockenheimring specifically to cover the RS Driver’s Challenge. Much to my delight, Audi elected to bring more than half a dozen new B7 RS 4’s to the event. After seeing an Imola Yellow RS 4 with Audi plates at my hotel the night before, I knew I was going to be spending much of the next day trying to talk my way into the driver’s seat.

I spent the next morning and early afternoon watching B5 RS 4’s, RS6’s, and a small handful of B7 RS 4’s circle around the track. It was very interesting to see the vastly different cars on the track all at the same time. Also entertaining were the B7 RS 4 safety/pace cars which led the first few laps of each session. These were the same specially prepared RS 4’s which I had seen earlier in the year at Le Mans – complete with modified exhaust systems, lowered suspensions and the requisite assortment of flashing lights, stickers, and safety equipment. The baritone bark of the safety cars made the standard production RS 4’s sound almost tame in comparison. As pace cars they are a worthy advertisement for Audi and really show off the beast that lies within. I’d be lying if I didn’t admit that the safety cars at 8,000+ RPM’s weren’t some of the sexiest V-8 noises I’ve ever heard.

Between the morning and afternoon driving sessions, there was a break in the action and all of the Audi cars had returned to the pit area. I took advantage of the situation and arranged a test drive through one of the quattro GmbH employees. I was told there would be a car available for me to try, but I would have to wait until one of the event participants returned from his test drive. Fair enough. In the meantime, I managed to get a ride with another RS 4 while an Audi employee took off to fill up the gas tank. I ditched my camera gear and eagerly jumped in.

The first thing I noticed about the RS 4 was how firm yet compliant the suspension was. These two seemingly contradictory attributes are what suspension calibration engineers actually strive for when developing a car with sporty intentions. The springs must be stiff in order to control body motions (lean, pitch, roll), yet the damping must be compliant enough to absorb undulations, bumps, and changes while keeping as much tire on the road surface as possible. With the first set of bumps we went over, it was immediately clear how stiff and solid the B7 platform really is. Driver comfort also ranks as a high concern in a car such as the RS 4. Performance with refinement is the key.

After a short tease, I was back in the pits waiting for my car to return. Of course the driver of the car I was promised was late in bringing the RS 4 back. Can I blame him? Certainly not.

Finally, my car had returned. The particular car I was given was Sprint Blue with 19-inch wheels, standard (US) steering wheel, black Recaro “Schalensitze” (shell seats), and navigation. Sitting in the driver’s seat for the first time, I took a few moments to familiarize myself with the cockpit. The interior was exactly what one would expect from Audi; it was very rich and built of solid materials. Every button push and switch throw felt precise and moved with intent. Upon entering the cabin, the driver is greeted with a full color RS 4 logo within the central driver information screen (DIS). The layout is immediately familiar to anyone who has owned a modern Audi. The only mystery was an “S” button on the upper dash next to the “ESP” defeat switch.

Finding a comfortable seating position with the manually adjusting Recaro seats and tilting/telescopic steering wheel was very easy. The steering wheel felt thick and noticeably smaller in diameter than the sport steering wheel in my B5 S4.

At this point, I was ready to fire up the 4.2 liter V-8 mill. I have driven a few B6 S4’s before, but I knew this car was going to be very different. After turning the ignition key to the “on” position, I reach down to the center console and pressed the (somewhat trendy these days, but slick nevertheless) “Engine Start” button. Instantly, the engine fired to life with the electronic throttle system gently blipping the revs to about 2,000 RPM, then settling into a very smooth idle. A message on the DIS reminded me that a maximum of 7,000 RPM was allowed, as the engine oil was still cold. Understood. I wouldn’t rev a cold engine to even half of that anyway. A nice addition was the oil temp readout at the bottom of the DIS.

As I eased the clutch in and selected first, I took note at the ease of the clutch disengagement and precision of the gearbox. I would have had to have driven a standard B6/B7 car back to back to assess any clear difference, but it’s quite obviously leaps and bounds better than my B5. The shifter precision is not quite yet at world-class levels (see Honda S2000 or BMW M3) evident by the slight bit of slop within the gates, but still has a smooth feel and consistent and easy engagement. I gently coaxed the RS 4 around the paddock area until the fluids were warm and was soon away from the excitement of the track event. On the way out I noticed how easy the steering was at low speeds. The power assist seemed to be quite strong at a parking lot crawl.

Just past the entrance to the Hockenheimring gate, I pulled into a small parking lot. The coolant gauge was happily pointing in the center and the oil was satisfactorily warm. Let the games begin!

I started out by revving the engine a little. The tuned V-8 instantly responded to the request of my right foot and wrapped up with authority. In fact, the first time I revved the engine I was flat out surprised how quickly it spooled up. I can only assume this improved throttle response is a direct result of Audi lightening up the reciprocating parts within the engine. I also would be unsurprised to find out that the flywheel was also lightened compared to the standard S4 V-8.

The effects of the lightened engine/flywheel parts can also be felt when taking up the clutch. There is a little less inertia to keep the engine going (meaning the revs also drop quickly when clutch is taken up) but the drive by wire system is quick to catch you to try to prevent a stall. A warning to those who drive this car: the engine actually revs so fast in neutral that it outruns the tachometer. You will be bouncing off the 8,250 rev limiter before the tachometer passes 7,000 RPM. Amazing. The sound at idle is very subtle. It sill has a deep V-8 gusto, but is very quiet and smooth. The car’s manners are impeccable. For an impression of the RS 4 idle and revving to idle, right click and "save-as" the video at the end of this article.

Just prior to setting off, curiosity got the best of me again. I had no idea what the “S” button was as I had never seen it in another Audi vehicle before. Instantly after pressing the button, I could feel the side bolsters in the seat increase pressure with the application of extra lateral support. We’re talking about real grip here, not some subtle change. Also changed, but to a lesser extent was the tone of the exhaust note. Internal flaps are actuated within the exhaust system to provide a more sporting exhaust tone in the “S” mode. I am later told that throttle response is also increased with “S” mode activated, but I had not noticed this change.

As I make my way out to the countryside, I marvel at the smoothness and flexibility of the motor. There is sufficient grunt available at 1,000 RPM, and the engine is actually just as happy to operate at this speed. Obviously, this type of driving is not what the RS 4 is designed for, so I’m anxiously making my way to the winding rustic roads that surround the Hockenheimring.

 With an open road ahead of me, I am finally able to wind out the lovely motor. Gently rolling it out in first gear, the RS 4 sprung ahead when I floored the accelerator and instantly sprinted through the revs. An eyeblink before the 8,250 RPM rev limiter, I selected 2nd gear and repeated the process over again. I am shoved into the seat as the quattro AWD drivetrain provides perfect grip and the strong V-8 feeds me instant torque. I am able to run the car through 3rd gear to redline before slower traffic forces me to brake. Thrust is smooth, very smooth. The pull through the rev range was very consistent and turbine-like. The engine doesn’t explode with power on the top end like many high-strung powerplants, but rather the driver is greeted with a firm shove all the way from about 2000 RPM to redline. The power delivery is always mannerly and never brutal. As usual for an Audi, the car is deceptively fast. If any engine is to be described as sewing machine smooth, this is it. It happily spins faster and faster with no signs of being stressed or strained. It doesn’t have the raw power, torque or acceleration of a modified B5 S4, but the engine is just so much more refined. Once the magazines publish instrumented testing, I expect 0-60 times around 4.7 seconds and a quarter mile time of 12.8-13.0 @ 106-108 mph.

Soon, I am met with the A6 Autobahn. On the cloverleaf highway entrance, I hustle around the ramp and try to get a feel for the cornering. Body controls are flat and in check. Steering firms up compared to slow speeds, but could use slightly more feel. Once I am on the Autobahn, I am able to run the car up to triple digit speeds a few times. Traffic wouldn’t allow me to get up over 235 km/h (146 mph) however. In any case, stability remained excellent throughout.

Also very impressive were the new 6 piston brakes (lifted from the Lamborghini Gallardo) with 365 mm cross drilled rotors up front and 324 mm rotors in rear. Throw out the anchor and you are greeted with a very solid and progressive pedal feel. After a handful of Autobahn stops, no signs of fade were detected, although one would have to be on a racetrack to really test the limits of the braking system. After watching two of Audi’s DTM racing drivers hammer lap after lap out with a stock braking system, I can confidently say they are the best to ever come standard from the factory on an Audi car.

On the way back to the Audi pits, my chosen route takes me through some more windy country roads. During this part of the drive I could really feel Audi’s Dynamic Ride Control (DRC) system at work. DRC is a mechanical system, which diagonally links dampers on opposite corners together. The direct effect is that body roll, pitch, and dive is drastically reduced. This was not only apparent when driving the car, but also when comparing the new RS 4 to the old RS 4 out on the track. Through the corners, I was only pushing the car to 8/10, so any effect provided by the new asymmetrical 40/60 quattro differential could not be felt. It is my opinion that it would take 10/10 racetrack driving, or a low traction situation to realize the benefits of the 40/60 quattro versus the former 50/50 system. Neither of those options were available to me.

Once reentering the Hockenheimring grounds, I took a slight detour to “play” with the car a little at a large, open parking lot. In a skidpad type test, I gradually increased the cornering speed to get a feel of the car at the limit of adhesion. The amount of grip the new RS 4 generates is quite impressive. However, the “at the limit” handling still leaves room for improvement in my opinion. When the limits are exceeded, you are greeted with safe and dull understeer. Even with the ESP off, I was not able to get the tail out with the new 40/60 differential. One blame factor here is the relative lack of torque compared to the grip available. Another factor lies within the suspension calibration. I feel Audi still has some ways to go if they intend to compete with the driving involvement/experience of the RWD competition. This new RS 4, however, is a step in the right direction and certainly an improvement over a stock B5 RS 4 in terms of suspension.

Soon I’m back at the Audi and quattro GmbH paddock. Like the gentleman before me, I’m back slightly late and I’m not quick to relinquish the keys to the new RS 4. However, the yellow gas pump on the DIS and the 10 km to empty tell me it’s probably time to give it back. On a side note, a totally unscientific gut feeling on the gas mileage tell me the fuel consumption is good given how hard I was driving the car. This is undoubtedly one of the side benefits observed from the FSI injection system. Given the lighter weight and FSI technology, I would be very surprised if the fuel consumption isn’t better than the current S4.

Overall, my experience with the new RS 4 was very positive. The fit, finish, and construction of the car are first rate. There are many wonderful touches like the carbon fiber trim on the dash and under the hood (over the throttle body), red valve covers, excellent navigation system, and seats that are among the world’s best. The 4.2 liter V-8 is a jewel and a pleasure to rev all the way to its lusty 8,250 RPM rev limit. I have nothing but good to say about the brakes.

There are also a few things I think Audi can still improve on. The thrilling torque present on Audi’s turbo cars is missing. The stock exhaust could use a little more “oomph”. I wish the “at the limit” handling was a little more neutral. Lastly, I wish Audi could have gone a little further with weight savings compared to the S4. Potential owners are advised: part of the weight savings was achieved through elimination of the spare tire. The battery lies within the spare tire compartment in an attempt to improve weight distribution.

Overall, the new RS 4 is quite a technological achievement for Audi. It may not be a class leader in terms of performance, but it makes up in overall competence and versatility. The car will perform well 365 days a year in rain or shine. It will also carry 5 people and a trip’s worth of luggage. If you’re looking for the ultimate in 4-door, V-8, AWD performance your list will be quite short. If you are looking for a high performance sedan, which doesn’t compromise refinement and luxury, the RS 4 may be the perfect fit for you.

Type: V-8
Displacement cu in (cc): 254 (4163)
Bore in (mm):  3.33 (84.5)
Stroke in (mm):  3.65 (92.8)
Compression ratio:  12.5:1
Power bhp (kW) at RPM: 420(323) / 7800
Torque lb-ft (Nm) at RPM: 317(430) / 5500
Redline at RPM: 8250
Brakes & Tires
Brakes F/R: ABS, vented disc/vented disc
Tires F-R: 255/40 R18
Driveline: All Wheel Drive
Exterior Dimensions & Weight
Length × Width × Height in: 179.0 × 70.8 × 55.2
Weight lb (kg): 3637 (1650)
Acceleration 0-62 mph s: 4.8
Top Speed mph (km/h): 152 (250)
Fuel Economy EPA city/highway mpg (l/100 km): 10/20 (13.7)