The B5 Audi S4 was the discreet 1990s performance car that made a compact executive saloon feel like a turbocharged grand tourer. Introduced in Europe in 1997, it combined a 2.7-litre twin-turbo V6, permanent quattro four-wheel drive and either saloon or Avant bodywork. Its 265PS European output sat below the later RS4, but the S4 created the engineering base from which that landmark car grew.
Today it is often discussed as a tuning platform or as the RS4’s understudy. That understates its importance. The B5 S4 was a complete performance model in its own right, with a broad spread of torque, six-speed manual gearbox, understated styling and the ability to cover ground rapidly in almost any weather.
From five-cylinder S cars to the B5 S4
Earlier Audi S models had been based on the larger 100 and A6 and were famous for turbocharged five-cylinder engines. The B5 A4 changed the direction of the range. Audi moved its performance badge into the compact executive class and adopted a new V6, giving the S4 a smaller, more contemporary package.
The engine displaced 2,671cc, used five valves per cylinder and one small turbocharger for each bank. Audi’s official RS4 history records the S4’s European output as 195kW, or 265PS. North American cars were rated differently at 250hp, so figures should always be matched to market specification.
The 2.7 biturbo V6
The S4’s defining feature is not merely peak output but delivery. Two compact turbochargers helped the V6 produce strong torque without the obvious single-turbo lag associated with some earlier performance cars. A six-speed manual was the enthusiast’s choice, although a five-speed Tiptronic automatic was also available in several markets.
The engine later became the foundation for the B5 RS4. quattro GmbH and Cosworth Technology redesigned major components, enlarged the turbos and intercooling and raised output to 380PS. That relationship confirms how much potential Audi had built into the original S4 architecture, while also showing why an S4 and RS4 should not be treated as mechanically identical.
Quattro and the B5 chassis
Unlike transverse-engined Audi models of the period, the longitudinal B5 used a centre differential for permanent four-wheel drive. The system gave the S4 reliable traction and a secure high-speed character, qualities that suited its understated road-car mission.
Its suspension and brakes were uprated from the A4, but the car remained deliberately usable. The S4 was not intended to feel like a stripped homologation special. It was a fast, refined executive car that could be driven every day, carrying four adults or a useful load in Avant form.
Saloon and Avant
Both body styles are central to the S4 story. The saloon has the compact proportions of the B5 A4 and looks especially anonymous without bright paint. The Avant offers the practicality that later became inseparable from Audi’s performance image.
Neither is dramatically styled. Deeper bumpers, side skirts, discreet S badges, alloy mirrors on some cars and model-specific wheels are the main clues. That restraint is a major reason enthusiasts still value the B5: it delivers considerable performance without needing to advertise it.
A car frequently modified
The biturbo V6 responds strongly to software and hardware changes, so many S4s have been modified. That can create very fast cars, but it also makes accurate description important. Turbochargers, fuelling, intercooling, exhaust, clutch, gearbox and brake specification should be documented rather than assumed.
A standard-looking body does not guarantee standard mechanicals. Conversely, a carefully engineered upgraded car may be more coherent than one carrying a collection of unrelated parts. Provenance and invoices are therefore central to understanding an individual B5 S4.
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Why the B5 S4 matters
The B5 brought the S badge into a smaller class, introduced the 2.7 biturbo V6 and proved there was room between an ordinary A4 and a hand-finished RS model. It gave Audi a direct rival to compact performance saloons while retaining quattro traction and Avant practicality.
Its legacy also runs through the RS4. The later car is more powerful, rarer and more visibly special, but it exists because the S4 first established the platform, drivetrain and audience.
Frequently asked questions
What engine does the B5 Audi S4 use?
It uses a 2.7-litre, 30-valve V6 with two turbochargers. European cars were rated at 265PS; North American cars carried a 250hp rating.
Was the B5 S4 available as an Avant?
Yes. Audi produced both saloon and Avant estate versions. Availability and transmission choices varied by market.
Is the B5 S4 the same as an RS4?
No. The RS4 was based on the S4 but was extensively re-engineered by quattro GmbH and Cosworth Technology, with 380PS, a wider body, different chassis hardware and Avant-only production.
Did every B5 S4 have a manual gearbox?
No. A six-speed manual was widely offered, but a five-speed Tiptronic automatic was also available in several markets.
Why are so many B5 S4s modified?
The biturbo V6 has substantial tuning potential and the quattro drivetrain can deploy increased power. Modifications should be supported by clear evidence of compatible fuelling, cooling, transmission and braking upgrades.
Research sources
- Audi: From bestseller to legend
- Audi: 50 years of the five-cylinder
- Wikimedia Commons creator and licence records linked beneath each photograph.
Specifications and equipment varied by year and market. Confirm an individual car from its VIN, engine code and original documents.
Continue the Audi story
Browse the Rare & Performance Audi hub, or read about the five-cylinder Audi S2 and the Porsche-assisted Audi RS2 Avant.
