Audi RS 4
||This article may contain an excessive amount of intricate detail that may only interest a specific audience. (July 2011)|
Audi RS 4 (B7) quattro Avant
(a private subsidiary of AUDI AG)
|Layout||Longitudinal front engine,
quattro permanent four-wheel drive
|Platform||Volkswagen Group B platform series|
The Audi RS 4 quattro is the top tier and highest performing version of some specific generations of the Audi A4 range of automobiles. It is a sports-focused compact executive car (often called sport compact in some countries), produced by Audi's high-performance private subsidiary quattro GmbH, in limited numbers, for German car manufacturer AUDI AG, part of the larger Volkswagen Group. It slots distinctly above the Audi S4, as the fastest, most sports-focused model based on the A4's "B" automobile platform. The RS 4 made a comeback in 2012, in Avant form only based on the Audi A4 Avant.
The original B5 version was produced only as a five-door five-seat "Avant", Audi's name for an estate car/station wagon. The second version, the B7, was released initially as a four-door five-seat saloon/sedan, with the Avant following a short while later. A two-door four-seat Cabriolet version was subsequently added. Furthermore, their unique internal combustion engines are all front-mounted, and are longitudinally oriented. The transmission is mounted immediately at the rear of the engine in a longitudinal orientation, in the form of a transaxle, and contains both a center and front differential.
The "RS" initials are taken from the German: RennSport—literally translated as "racing sport", and is the Audi marque's highest trim level, positioned above the "S" model specification of Audi's regular model line-up. Like all Audi "RS" cars, the RS 4 pioneers some of Audi's latest advanced technology, and could therefore be described as a "halo vehicle". Furthermore, it is only available with Audi's Torsen-based "trademark" quattro permanent four-wheel drive system.
B5 (Typ 8D, 2000–2001)
|Predecessor||Audi RS2 Avant|
|Successor||Audi B5 RS 4|
|Body style||5-door Avant (estate/wagon)|
|Platform||Volkswagen Group B5|
|Engine||2.7 L V6 "biturbo" 2 × DOHC (ASJ/AZR)|
|Wheelbase||2,607 mm (102.6 in)|
|Length||4,525 mm (178.1 in)|
|Width||1,799 mm (70.8 in)|
|Height||1,386 mm (54.6 in)|
|Kerb weight||1,620 kg (3,571 lb)|
|Related||Audi B5 A4
Audi B5 S4
The original B5 Audi RS 4 Avant quattro (Typ 8D) was introduced by Audi in late 1999, for main production and sale from 2000, as the successor to the Porsche / quattro GmbH joint venture-developed Audi RS2 Avant. The vehicle, like its RS2 predecessor, was available only as an Avant and was built on an existing platform, in this case the Volkswagen Group B5 platform shared with the A4 and S4. Retail price was around DM 103,584. The RS 4 was available for sale in most of Europe, parts of Asia and in some Latin American countries.
Audi produced 6,030 units between 1999 and 2001.
B5 bodywork and styling
Although related to the Audi B5 S4, many of the outer body panels were altered, with wider front and rear wheel arches, to allow for the wider axle track on the RS 4. With unique front and rear bumpers and side sills, and the rear spoiler from the S4 Avant, the aerodynamic modifications achieved a drag coefficient of Cd 0.34. Although the B5 S4 came in a saloon car body style, the B5 RS 4 was only available in the Avant version.
Luggage space, measured according to the industry standard VDA method was 390 litres (13.8 cu ft) with the rear seats in the upright position, and 1,250 litres (44.1 cu ft) with the seats folded flat.
The engine was developed from the 2.7 litre 90° V6 'biturbo' used in the B5 S4. It displaced 2,671 cubic centimetres (163.0 cu in) and had five valves per cylinder. The parts code prefix was 078 and the identification codes were: early version, 2000 (EU2 compliant): ASJ, and later version, 2000-01 (to EU3 standard): AZR. This engine was developed and manufactured in the UK by Cosworth Technology (now known as MAHLE Powertrain). It featured enlarged intake and smaller exhaust ports on the two Cosworth cast aluminium alloy ALSi7mg cylinder heads, two parallel BorgWarner K04-series turbochargers, two larger side-mounted intercoolers (SMICs), dished piston crowns, stronger connecting rods, larger intake ducting, enlarged exhaust system, and a re-calibrated engine management system. The modifications increased the engine's output from 195 kilowatts (265 PS; 261 bhp) and 400 newton metres (295 lbf·ft) of torque in S4 form to 280 kilowatts (381 PS; 375 bhp) at 7,000 revolutions per minute (rpm) and 440 newton metres (325 lbf·ft) at 6,000 rpm. The engine was controlled by a Bosch Motronic ME 7.1 electronic engine control unit (ECU), using a Bosch 'E-Gas' electronic drive by wire throttle. The engine had multipoint sequential fuel injection, a MAF, six individual single-spark coils and NGK longlife spark plugs. The engine oil was cooled by a dual oil:water cooler and an oil:air cooler.
A six-speed manual transmission (parts code prefix: 01E, identification code: FDP) (gear ratios—1st: 3.500, 2nd: 1.889, 3rd: 1.320, 4th: 1.034, 5th: 0.806, 6th: 0.684), cooled by a NACA duct in the engine undertray, and Audi's Torsen-based quattro system, using the Torsen T-2 "automatic torque biasing" (ATB) center differential, with a 50:50 default bias were standard. Final drive ratio was 4.111.
Even with a kerb weight weight of 1,620 kilograms (3,571 lb), the RS 4's powerful engine gave it the performance of a sports car. 100 kilometres per hour (62.1 mph) could be reached from rest in 4.9 seconds, 160 kilometres per hour (99.4 mph) in 11.3 seconds, and 200 kilometres per hour (124.3 mph) in 17.0 seconds. Top speed was electronically limited to 262 kilometres per hour (162.8 mph).
B5 brakes, wheels and tires
Brakes were also developed jointly in house by Audi's quattro GmbH, not by Porsche as with its predecessor, the RS 2. At the front they were radially vented and floating cast iron discs, 360 millimetres (14.2 in) diameter and 32 millimetres (1.26 in) thick, with double-piston floating calipers, and at the rear 312 millimetres (12.3 in) by 22 millimetres (0.87 in) discs with a single-piston floating caliper. The RS 4 needed less than 50 metres (160 ft) to come to a full stop from a speed of 110 kilometres per hour (68 mph).
The standard wheels were 18 inch alloys (8½×18" "9-spoke"), with 255/35 ZR18 high performance tyres. Optional "winter" alloy wheels were also available, at 18 inch (7½J×18"), with 225/40 R18 92V tyres.
Other B5 notable features
B7 (Typ 8E, 2006–2008) 
|Predecessor||Audi B5 RS 4|
|Successor||Audi B8 RS 4|
|Body style||4-door saloon/sedan,
5-door Avant (estate/wagon),
|Platform||Volkswagen Group B7|
|Engine||4.2 L V8 FSI 2 × DOHC|
|Transmission||6-speed Getrag manual|
|Wheelbase||2,648 mm (104.3 in),
Cabrio: 2,650 mm (104.3 in)
|Length||4,589 mm (180.7 in),
Cabrio: 4,555 mm (179.3 in)
|Width||1,816 mm (71.5 in),
Cabrio: 1,814 mm (71.4 in)
|Height||1,415 mm (55.7 in),
Cabrio: 1,391 mm (54.8 in)
|Kerb weight||saloon: 1,650–1,680 kg (3,638–3,704 lb),
Avant: 1,710 kg (3,770 lb),
Cabrio: 1,845 kg (4,068 lb)
|Related||Audi B7 A4
Audi B7 S4
There was no RS 4 built on the Audi "B6" platform that served as the basis for the Audi A4 between 2001 and 2005. However, after a long hiatus, the second Audi RS 4 quattro (Typ 8E), was built on Audi's "B7" A4 platform, by quattro GmbH in Neckarsulm, Germany. It was unveiled in February 2005 at Audi's 'quattro Night' celebration at the company headquarters in Ingolstadt, Germany.
An Imola Yellow RS 4 saloon came down a replica of a ski jump, then rotated several times on an ice rink, before coming to rest in the centre of the ice. After several minutes to allow the assembled media and guests to examine the car, the RS 4 climbed the ski jump and parked near the top. The ski jump was a homage to an Audi commercial from 1986; where an Audi climbed a ski jump in Finland to showcase its superior traction due to Audi's trademark quattro drivetrain.
The RS 4 became available to European customers in mid-2006. It was introduced at the 2006 North American International Auto Show in January, and arrived in June 2006 in North America. The production run of the B7 RS 4 was 2006 to 2008 inclusive, although only 2007 and 2008 model year were sold in the United States. To date, approximately 10,000 B7 RS 4s have been built, of which around 2,500 are in the USA.
The B7 RS 4 Cabriolet, available in Europe from late 2006 to 2008, was made available as a model year 2008 vehicle in the USA.
Audi factory numbers indicate that the B7 RS 4 saloon can accelerate from 0 to 100 kilometres per hour (0 to 62.1 mph) in 4.8 seconds, and arrive at 0 to 200 kilometres per hour (0 to 124.3 mph) in 16.6 seconds. Most European magazines recorded results in line with the November 2009 comparison of "ultimate sedans", in Road & Track, which recorded a 0 to 60 time of 4.5 seconds. This is consistent with the pattern of conservatism that is usually found in Audi's official performance numbers. For the Avant, 0 to 100 kilometres per hour (0 to 62.1 mph) is reached in 4.9 seconds. Top speed for all variants is "officially" electronically limited to 250 kilometres per hour (155.3 mph), though some owners have reported that the speed limiter is rather "liberal", conforming to the pattern of previous Audi "RS" cars, with genuine top speeds of 270 kilometres per hour (170 mph) being recorded.
B7 bodywork and styling
The B7 RS 4 is an almost complete departure from previous Audi "RS" cars, as it was initially available as a four-door five-seat saloon/sedan; with a five-door five-seat Avant (estate/wagon), and two-door four-seat Cabriolet (convertible) versions arriving later. Only the Audi RS 6 had taken this similar route (saloon and Avant) before; the previous RS 4 and RS 2 were available exclusively as Avants.
Constructed from fully galvanised steel in a monocoque (unitary/unibody) design, the B7 RS 4 uses lightweight aluminium for its front wings (fenders) and bonnet (hood). The saloon version features a drag coefficient (Cd) of 0.31, from a frontal area of 2.17 m2.
Like its B5 predecessor, visually, the B7 RS 4 differs from its related B7 S4, by having even wider flared front and rear wheel arches (fenders), to allow for a wider axle track. Over the B7 A4, it also includes two larger frontal side air intakes (for the two additional side-mounted coolant radiators). The trim on the saloon and roof rails on the estate are chrome as standard but can also be found in black with the addition of the Optic Pack which includes a black front grill, all exterior trim and black roof rails on the estate version. The B7 RS 4 also includes an optional adaptive headlights to complement the standard "Xenon Plus" (Bi-Xenon arc) High Intensity Discharge (HID) headlamps, which swivel around corners in conjunction with steering wheel movements. Also standard are daytime running lights (DRLs), found within the main headlamp housings, identical to its related B7 A4 and S4, and use a conventional tungsten filament bulb. An acoustic parking system with front and rear sensors is also a standard fitment. Unique carbon fibre interior trims, along with a lap timer within the central Driver Information System (DIS), aluminium pedal caps and footrest, and RS 4 logos complete the look.
In the saloon, luggage space, measured according to the VDA 'block method', is 460 litres (16.2 cu ft) with the rear seats in the upright position, and 720 to 833 litres (25.4 to 29.4 cu ft) with the seats folded flat (dependent on specification). For the Avant, 442 litres (15.6 cu ft) is available with the seats upright (under the retractable load cover), and 1,354 litres (47.8 cu ft) being available with the rear seats folded flat (loaded to the roofline). Kerb weight of the saloon variant starts at 1,650 kilograms (3,638 lb) (dependent on specification).
A BOSE ten-speaker sound system, with 190 watt output and automatic dynamic noise compensation (which replaces the 'GALA' found on earlier units), with "Concert II" radio and single CD player is standard in car entertainment (ICE) equipment. Factory fitted ICE options to complement the standard BOSE include the "Symphony II" system which features twin radio tuners, a single-slot loading six-CD changer and a cassette player all integrated into a double-DIN sized unit. Navigation option is the RNS-E "Audi Navigation System plus" DVD-ROM GPS satellite navigation, which includes a folding widescreen 6.5-inch screen, two SD-memory card readers, and MMI-like logic control.
B7 interior safety
To achieve maximum body stiffness with controlled deformation crumple zones, the B7 RS 4 features laser beam welding of major seams of the high-strength steel body shell, which helps improve overall structural rigidity, particularly in the "passenger cell", over traditional spot welding methods.
Two-stage driver and front seat passenger frontal airbags are standard, as is Audi's "sideguard" head protection curtain airbag system. This latter system completely covers all of the side windows, from the front 'A pillar' to the rear "C-" or "D pillars". The body-hugging Recaro shell-type RS race bucket seats (not available in North American markets), complete with electrically inflatable upper and lower side bolsters and adjustable lumbar support, are constructed so as not to need lower side airbags to comply with European crash safety standards. In North America, the only front seats available are the more traditional Recaro seats (identical to those in the B6 and B7 S4), which include lower side airbags; these were also available as a no-cost option in other markets. Lower side airbags are optional for the standard-fit Recaro rear seats. Front, and outer rear seatbelts include pyrotechnic belt pretensioners, whilst all belts include an excess load limit function.
The engine of the B7 RS 4 is started by an "Engine Start" button on the centre console and is based on the existing all-alloy 4.2 V8 from the B6 S4, and shares many parts, and Fuel Stratified Injection, with the 4.2 FSI V8 engine in the Q7. The engine includes new cylinder block construction, and is a highly reworked, high-revving variant (redline at 8,000 rpm; rev limit of 8,250 rpm).
The parts code and version is 079.D and the identification code is BNS.
The engine has increased crankcase breathing, a low-pressure fuel return system and a baffled oil sump, to prevent engine lubricant cavitation at high engine speeds and high-G cornering. It has four valves per cylinder (instead of five on the earlier variant) and two overhead camshafts on each cylinder bank (so it is 'quad cam') and these are driven by roller chains with variable valve timing  for both inlet and exhaust camshafts, along with a cast magnesium alloy fixed tract length intake manifold with adjustable tumble flaps (to improve low engine speed combustion). On 98 RON (93 AKI) Super-Unleaded petrol it produces 309 kilowatts (420 PS; 414 bhp) at 7,800 rpm  giving it a specific power output of 74.2 kW (100.9 PS; 99.5 bhp) per litre. Based on a kerb weight of 1,680 kilograms (3,704 lb), this results in a power-to-weight ratio of 184 watts per kilogram. This engine also produces 430 newton metres (317 lbf·ft) of torque at 5,500 rpm, 90 percent of the total torque being available between 2,250 and 7,600 rpm. (Using lower 95 RON (91 AKI) standard unleaded fuel slightly reduces engine output, and therefore performance, and slightly worsens fuel economy). Exhaust gas escapes through two '4-into-2-into-1' fan-branch alloy steel exhaust manifolds and four high-flow metallic sports catalytic converters, into twin oval tail pipes with integral dynamic silencer/muffler valves. The engine is controlled by two Bosch DI-Motronic MED 9.1 electronic engine control units (working as 'master' and 'slave', because of the high-revving nature of the engine), and uses Bosch 'E-Gas' electronic throttle control (also known as drive by wire), comprising throttle device, accelerator-pedal module, and ECU. The ignition system uses eight individual single-spark coils, using mapped direct ignition, with Bosch single iridium electrode or NGK triple-electrode long-life spark plugs. Ignition timing is monitored with the aid of four knock sensors. The engine complies with the Euro4 European emission standards. The saloon version produces 322-329 grams of CO2 per kilometre (g/km), and the Avant starts from 324 g/km.
A six-speed Getrag manual gearbox (parts code: 0A3, identification codes: HLD, JHM) is the only transmission available. The gear ratios are 1st: 3.667, 2nd: 2.211, 3rd: 1.520, 4th: 1.133, 5th: 0.919, 6th: 0.778.
The Audi B7 RS 4 was the only "RS" Audi powered by a naturally aspirated engine until the Audi RS5 was presented at the 2010 Geneva Motor Show. The RS5 also uses a 4.2 litre high revving V8, which puts out 450 horsepower, however the RS5 engine is based on the 5.2 liter V10 in the R8, and is not related to the RS4 engine.. The RS5 also dropped the Getrag 6-speed manual in favour of a 7-speed "S tronic" dual clutch semi-automatic.
Another focus of the B7 RS 4 was on the introduction of the latest development of Audi's 'trademark' quattro permanent four-wheel drive system. This utilised the 'third generation' asymmetric/dynamic Torsen T-3 'automatic torque biasing' (ATB) centre differential, featuring a 'default' 40:60 front-to-rear torque split under normal conditions. Audi stressed that this would result in a more neutral response in corners, and a more dynamic driving experience. Also, a more aggressive Torque Bias Ratio (TBR) was used, and set to 4:1, as opposed to 2:1 (and later variants 3:1 TBR) on standard A4. That means that one side of the differential can handle up to 80%, while the other side would have to only handle 20% of applied torque.
Traction is assisted by way of Audi's "Electronic Differential Lock" (EDL), which is a specific function of the Robert Bosch GmbH ESP 8.0 Electronic Stability Programme system. EDL monitors the rotational speeds of the left and right wheels across an individual axle, and if one wheel should rotate faster than the other (exceeding the pre-defined parameters), indicating loss of traction, or "wheel spin" on one wheel, the EDL applies the brakes to that individual spinning wheel, and thus results in transferring torque across the open differential to the wheel on the other side deemed to have grip, hence traction. Also included in the ESP 8.0 is "Anti Slip Regulation" (ASR)—Audi's name for Traction Control System.
The result of all these features is that under normal circumstances (driving straight on dry or even wet road surfaces) the car never loses traction, even when accelerating at full throttle in the first gear.
B7 suspension and steering
The B7 RS 4 also incorporates Audi's "Dynamic Ride Control" (DRC) "Sports Suspension" mechanism. The dampers (shock absorbers) are made for Audi by KW, and central reservoirs/valves made by KYB (Kayaba). In the RS 4 suspension, a fluid hydraulic linkage between diagonally opposing front and rear suspension dampers (left front to right rear, and vice-versa) is used to counteract vehicle pitch and roll. Lightweight magnesium/aluminium alloy multi-link suspension arms (four arm with virtual steering axis up front, and trapezoidal arm with unequal length track control arms at the rear) locate each hub/brake/roadwheel assembly in a controllable fashion, whilst minimising unsprung masses. Lightweight hollow tubular anti-roll bars are standard front and rear. Compared to standard B7 A4 models, the RS 4 features a 30 millimetres (1.2 in) lower ride height. An optional "Sports Suspension Plus" lowers the car by a further 10 millimetres (0.4 in), and marginally further stiffens the damper rates.
Axle track has also been increased over standard A4s; the front widened by 37 millimetres (1.5 in), to 1,559 millimetres (61.4 in) and the rear by 47 millimetres (1.9 in) to 1,569 millimetres (61.8 in).
Speed sensitive "servotronic" variable-assistance electro-hydraulic power assisted steering (PAS) is controlled from a compact flat-bottomed steering wheel, finished in perforated leather with mock-aluminium trim. The steering rack ratio is 13.1:1, and the turning circle is 11.1 metres (36.42 ft).
B7 brakes, wheels and tyres
The standard brakes on the RS 4 are of two-piece construction. The cast iron discs are cross-drilled and radially ventilated and float on aluminium alloy disc hubs. The two-piece disc construction reduces unsprung mass and also reduces the transmission of heat generated by the brakes to the wheel bearings.
The front discs are 365 millimetres (14.4 in) in diameter and 34 millimetres (1.34 in) thick, and use gloss black Brembo monoblock eight-opposed-piston fixed calipers. These and the transmission are supplied with a cooling airflow directed from NACA ducts located in the engine front undertray.
The rear brakes are drilled, vented and floating 324 millimetres (12.8 in) by 22 millimetres (0.87 in) iron discs, with gloss black Lucas-Girling TRW single piston floating calipers with an integrated mechanical handbrake mechanism.
A lighter, and higher performing, "Audi ceramic" front brake system was an option from 2007 model year onwards (and only with 19 inch wheels). It comprised cross-drilled, radially vented and floating Carbon fibre-reinforced Silicon Carbide (C/SiC) composite SGL Carbon discs, 380 millimetres (15.0 in) diameter and 38 millimetres (1.50 in) thick, with grey Brembo monoblock six-opposed-piston fixed aluminium alloy calipers. The discs have a much greater tolerance to thermal differences, virtually eliminating brake fade, and have a duration of five times greater than conventional iron discs. The ceramic brakes also reduce unsprung mass by around 50% and thereby improve steering response and overall handling.
A specifically 'tuned' "sport-biased" Bosch ESP 8.0 Electronic Stability Programme is standard, and includes Anti-lock Braking System (ABS) and Electronic Brakeforce Distribution (EBD), and Brake Assist (BA). This ESP system has three user-selectable settings: the standard default full protection mode, increased slip mode (which turns off the ASR and EDL), and ESP fully off. A useful feature of the ESP 8.0 is 'disc wiping', whereby in wet weather the ESP system applies the brakes frequently but momentarily. This removes water from the disc and pad surfaces, and helps to maintain the braking performance of dry weather. This operation is undetectable by the driver.
In the UK and Japan, the standard wheels are 19 inch alloy wheels (9Jx19" ET29 "7-arm double spoke") with 255/35 ZR19 96Y XL (eXtraLoad) high performance tyres. This 19" wheel and tyre package was an option for the North American, and some European markets. Factory supplied tyres included Continental SportContact 3, Michelin Pilot Sport PS2, or Pirelli P-Zero Rosso — although many owners have questioned the load-carrying abilities of the Pirellis (from unexplained sidewall failures and dubious dynamic stability), opting for the more durable Michelins at replacement time. A no-cost option of 18 inch alloy wheels (8½Jx18" ET24 "5-spoke design") with 255/40 ZR18 Y XL tyres was also available, and these are standard in North American markets. A winter wheel and tire package was also available as an option, and included 245/40 R18 96V Dunlop SP WinterSport 3D tyres.
A direct-acting Tyre Pressure Monitoring System (TPMS) is standard fitment. This system monitors the pressure in all four tyres every three seconds, and when any loss in pressure is detected, audible and visual warnings are given to alert the driver via the Driver Information System (DIS) in a timely manner.
Other B7 notable features
Other notable features to be found as standard equipment on cars for non-North American markets are the smaller, flat bottomed steering wheel (complete with "Sport" button), body-hugging Recaro shell-type race bucket seats complete with electrically inflatable upper and lower side bolsters, and carbon-ceramic brakes. The B7 Audi RS 4 sold in Europe has roll-up windows for the rear doors although its USA-market counterpart has power windows for all doors.
B7 crash testing
The North American Insurance Institute for Highway Safety (IIHS) crash tested the B7 RS 4s sibling, the B7 A4, and awarded it "Double Best Pick" for frontal and side crashes—beating illustrious rivals such as the BMW 3 Series, the Mercedes-Benz C-Class, and even the Volvo S60.
The Audi RS 4 won Top Gear's Most Surprising Car of the Year in 2005. In 2007, the Audi RS 4 was the winner in the "World Performance Car" category of the International World Car of the Year (WCOTY). It beat illustrious rivals, including its larger sibling, the Audi C6 S6, the Porsche 911 Turbo, Porsche 911 GT3, Ferrari 599 GTB, and Jaguar XKR.
|Predecessor||Audi B7 RS 4|
|Body style||5-door Avant (estate/wagon)|
|Engine||4.2 L (4,163 cc) V8 FSI 32 valve|
|Wheelbase||2,811 mm (110.7 in)|
|Length||4,719 mm (185.8 in)|
|Width||1,826 mm (71.9 in)|
|Height||1,415 mm (55.7 in)|
|Kerb weight||1795 kg|
|Related||Audi B8 A4
Audi B8 S4
The Audi RS 4 Avant uses the same normally aspirated V8 engine that powers the RS 5 Coupe. The 4,163 cc powerplant produces 450 hp Its torque of 317.15 lb-ft is available from 4,000 to 6,000 rpm. The RS 4 Avant accelerates from zero to 100 km/h (62 mph) in 4.7 seconds on its way to a governed top speed of 250 km/h (155 mph).
Top traction: quattro drive with crown-gear center differential Like every RS model from Audi, the RS 4 Avant comes standard with quattro permanent all-wheel drive. The heart of this system is the crown-gear center differential. This compact and lightweight component can vary the distribution of power between the front and rear axles immediately, smoothly and over a wide range, with up to 70 percent flowing to the front or as much as 85 percent to the rear. The default 40:60 ratio of the rear-biased configuration ensures sporty handling.
The self-locking crown-gear center differential works together with the torque vectoring system, which acts on all four wheels. If the load on the inside wheel is reduced too much while the car is being driven dynamically, the torque vectoring system brakes it slightly before unintended slip can occur. Audi offers the sport differential, which uses two superposition stages to actively distribute the power between the rear wheels, as an option.
Ingolstadt - A modern classic from Audi is making a comeback: The third-generation RS 4 Avant combines potent performance with a high level of everyday practicality. It’s 4.2-liter V8 produces 331 kW (450 hp); the seven-speed S tronic and quattro permanent all-wheel drive transfer that power to the road.
The Audi RS 4 Avant uses the same high-revving, normally aspirated V8 engine that powers the RS 5 Coupe. The 4,163 cc powerplant produces 331 kW (450 hp) at 8,250 rpm for a specific output of 108.1 hp per liter. Its maximum torque of 430 Nm (317.15 lb-ft) is available from 4,000 to 6,000 rpm. The responsive V8 with its red-painted cylinder head covers accelerates the RS 4 Avant from zero to 100 km/h (62.14 mph) in 4.7 seconds on its way to a governed top speed of 250 km/h (155.34 mph). This can be increased to 280 km/h (173.98 mph) upon request.
Hand-built at Audi’s plant in Györ, Hungary, the 4.2 FSI engine combines its impressive power with exemplary efficiency, consuming on average less than 11 liters of fuel per 100 km (21.38 U.S. mpg).
With its high efficiency and long top gear, the standard seven-speed S tronic also contributes to the vehicle’s good fuel economy. Drivers can let the lightning-fast dual-clutch transmission shift automatically or change gears manually using the selector lever or the paddles on the steering wheel. For explosive starts, drivers can also activate Launch Control, which manages the engagement of the clutch at an optimum starting speed and minimum wheel slip. 
Speed World Challenge
The B7 RS 4 was planned to replace the C5 RS6 in the SCCA Speed World Challenge, but after Champion Racing had prepared the car, it was decided not to compete in the series, due to rule changes imposed by the Sports Car Club of America (SCCA) on Audi concerning 4WD systems, wheels size, and engine power output. Rather than scrapping the fully built Speed World Challenge RS 4, Champion and Audi used the car as a part of the American Le Mans Series Vitesse Program, which highlights the technology link between race cars and conventional series production road cars.
- "BMW M3 vs. Audi RS4 vs. Cadillac CTS-V vs. Lexus IS-F vs. Mercedes C63 AMG". The Truth About Cars. Retrieved 2012-05-17.
- "Audi Self-Study Programme SSP245 - Audi RS 4 (B5)". AUDI AG.
- Bosch Automotive Technology Motronic for manifold injection
- Bosch Automotive Technology Electronic throttle control (ETC/EGAS) for manifold injection
- 4_tech_data.doc "Audi RS 4 Saloon - Technical Data" (MS Word document). AUDI AG. Fortitude.com. February 2005. Retrieved 14 September 2009.
- "Geneva Motor Show: Audi RS 4 - The Sports Car for 365 Days a Year". AUDI AG. VWvortex.com - Audi News. 1 March 2005. Retrieved 14 September 2009.
- "'quattro Night' - B7 RS 4 world introduction". AudiWorld. AudiWorld.com. 27 February 2005. Archived from the original on 31 December 2009. Retrieved 7 January 2010.
- Kott, Douglas (2 November 2009). "Ultimate Sedan Comparison". Road & Track. Retrieved 2010-04-18
- Bosch Automotive Technology Variable valve timing
- Bosch Automotive Technology DI-Motronic for direct gasoline injection
- Bosch Automotive Technology Electronic throttle control (ETC/EGAS) for direct gasoline injection
- "2011 Audi RS5 - First Drive Review - Auto Reviews". Car and Driver. Retrieved 2011-06-17.
- Bosch Automotive Technology Electronic Stability Programme ESP
- December 2007 PHOTOGRAPHY BY ANDREAS LINDLAHR. "2008 BMW M3 vs. 2007 Audi RS 4, 2008 M-B C63 AMG Comparison Tests - Page 2". Car and Driver. Retrieved 2012-05-17.
- http://www.quattroholic.com/2012/02/audi-rs4-avant-b8-officially-revealed.html/ref>==B8 (Typ 8K, 2012–)==
- "Audi RS4 Avant (B8) officially revealed Program".
- "Hot Laps at Miller: The ALMS Vitesse Program". AudiWorld. AudiWorld.com. 18 May 2007. Archived from the original on 31 December 2009. Retrieved 7 January 2010.
|Wikimedia Commons has media related to: Audi RS 4|
- Audi.com official corporate website
- "Sinister Beauty" an official Audi UK microsite
- Audi B7 RS4 test drive and review at AudiWorld.com
- First Abt tuning for Audi RS4 at AutoYa.Info
- Video Audi RS4 vs. Porsche 911 Carrera 4S
|Audi, a marque of the Volkswagen Group, car timeline, North American market, 1980–present|
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|4000 CS quattro||S4 (8D/8E/8H/8K)|
|Mid-size car||5000 (43)||100 / 200 / 5000 (44)||100 / A6 (4A)||A6 (4A/4B/4F)|
|Ur-S4||Ur-S6||S6 (4B)||S6 (4F)|
|Full-size car||V8 (4C)||A8 (4D/4E/4H) / S8 (4D/4E)|
|Coupé||Coupé (81)||Coupe Quattro (89)||A5 / S5 (8T)|
|Coupé||TT Coupé (8N)||TT Coupé (8J)|
|Roadster||TT Roadster (8N)||TT Roadster (8J)|
|Convertible||Cabriolet (8G)||A4 Cabriolet / S4 Cabriolet (8H)||A5 / S5 (8F)|
|Sports car||Quattro (Ur-Quattro)||RS6 (4B)||RS4 (8E/8H)|
|Crossover||allroad quattro (4Z)|
|Mid-size SUV||Q5 (8R)|
|Full-size SUV||Q7 (4L)|