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 theVolkswagen 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.

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 trackon the RS 4. With unique front and rear bumpers and side sills, and the rearspoiler from the S4 Avant, the aerodynamic modifications achieved a drag coefficient of C_d 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 ALSi7mgcylinder heads, two parallel BorgWarner K04-series turbochargers, two larger side-mountedintercoolers (SMICs), dished piston crowns, stronger connecting rods, larger intake ducting, enlarged exhaust system, and a re-calibrated engine management system. The modifications increased the engines output from 195 kilowatts (265 PS; 261 bhp) and 400newton 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 aNACA duct in the engine undertray, and Audis 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 4s 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).

Brakes were also developed jointly in house by Audis 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.

The B7 RS 4 is an almost complete departure from previous Audi "RS" cars, as it was initially available as a four-door five-seatsaloon/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 (C_d) 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.

o 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 Audis "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.