|January 28, 2011
Audi RS5 - Short Take
By: Kris Hansen
How do you improve on one of the best all around cars Audi have ever built, the S5? One would think it would be a difficult task, yet Audi has managed to do it quite well indeed.
Itís called the RS5.
Itís not any kind of secret that the editors of AudiWorld are in love with the A5/S5 coupe, in a big way. Itís the kind of car that takes your breath away when you see one in traffic. It should therefore come as no surprise that news of the RS5 coming into existence sent our pulse rates racing. The overall appearance of the RS5 is a bit more aggressive than the S5, with much deeper chin spoiler and air inlets, not to mention the RS specific honeycomb grill. The RS5 has slightly wider hips, with a bit of flare on the fenders making the car look fantastically muscular. The rear bumper skin is different on the RS5 as well, with grillwork that matches the front grill, and different exhaust outlets. Also unique to the RS5 is a small pop up spoiler, not at all unlike the one in the R8, which lifts up at speed, and tucks back automatically when the car comes to a stop.
The interior of the RS5 would be familiar to any A5/S5 owner. The car we tested had the ďstandardĒ high back sports seats, which we found to be supremely comfortable and supportive, yet grippy enough to hold us in during some play time. Other cars we saw were fitted with much sportier and much narrower sports seats, which in all honesty are sexy, but snug for our taste. The steering wheel in the car we drove was wrapped in perforated leather, and seemed thicker than we remembered from the last S5 we drove, and we liked how it felt in hand.
Once inside, a quick tap of the ďStart EngineĒ brings the 450hp 4.2 liter FSI direct injected V8 to life, and fills the cabin with one of the nicest engine sounds weíve ever heard. Slipping the standard 7 speed dual clutch S-tronic into D, and getting underway is effortless and smooth. Once we got on the open road and tipped into the throttle though, the car took on a whole new character. The exhaust becomes very snarly, and while not loud or droning, it sounds really really good, and hammers home the sporting intent of the RS5. The thrust from this car is positively intoxicating. Audi say that 0-100kmh (62mph) happens in 4.6 seconds, which means that the 0-60 should be closer to 4 flat, which puts the RS5 in at roughly the same acceleration as the R8 4.2. Itís very very quick, even on the snow tires our car was fitted with.
The best part of the RS5 is the way it coddles itís passengers at all times. Even considering the high capabilities of the car, itís never harsh, never loud, never jarring. Even at high speeds, itís quite possible to have a nice civilized conversation without shouting.
We didnít have a lot of chances to push the limits of the car, other than on the ice track, which showed off the wonderful new technologies that the RS5 is fitted with, such as the new Crown Gear center differential, and the optional Sports Differential.
The RS5ís center differential contains two rotating crown gears (so named because of the crown-like arrangement of their teeth. Basically a crown gear is a flat disc with teeth on the face of the disc as opposed to the edge of the disc). The rear crown gear mates to the rear propeller shaft at itís center, which then connects to the differential at the rear axle. The front crown gear outuputs power to the front-axle differential in a mirror image of the rear. The crown gears mesh with four pinion gears which are sandwiched between front and rear, at right angles to each other, and driven by the differentialís housing, which is connected to the transmissionís output shaft. Meanwhile, there are also friction discs between the housingís outer cases and the back sides of the crown gears, which come into effect during slippage.
Under normal driving, both crown gears rotate at the same speed as the differential housing which drives them with the pinion gears. The pinion gears are designed in such a way that as a default, 60 percent of engine torque is sent to the rear-axle differential and 40 percent to the front.
As soon as one axle loses grip, there is suddenly a speed difference between the crown gears within the differential housing. Axial forces cause the adjacent friction disc packages to press against one another, which locks up the differential resulting in the majority of the torque being redirected to the axle achieving better traction. Up to 85 percent of engine torque can flow to the back rear axle, and up to 70 percent to the front axle.
The Crown Gear center differential is 100% mechanical, and even though itís much more effective than the previous center differentials, itís actually more compact and lighter.
When combined with the other electronic wizardry fitted to the newest Audis, the cornering grip is astounding. The latest such electronic handling aid is called Torque Vectoring. Basically an upgraded ESP system, torque vectoring reads steering angles, lateral acceleration, and wheel slip to aid in cornering in lower grip situations.
Essentially, if under cornering the inside tires lose grip at all, the car applies brake pressure to those wheels, and helps the car maintain its handling neutrality and stability in corners with lower grip. It really helps the car handle well in all situations.
When you add in the active sports rear differential, the car corners like its on rails. This rear diff has the ability to overdrive the outside wheel in a corner, which as you might expect, really helps the front end turn in. On the ice skid pad at Mecaglisse, it drove around as if it was on a much grippier surface. It was truly amazing, and the difference could be instantly felt when it was switched off.
Weíre looking forward to spending a little more time, and getting more in depth with the RS5!