The first Audi S4 was not a compact sports saloon. It was the discreet flagship of the C4 Audi 100 range. Introduced in 1991 with a 230PS turbocharged five-cylinder engine and quattro four-wheel drive, it established the S4 name before a 1994 facelift turned the same basic model into the Audi S6.
The original S4 formula
Audi took the large, restrained C4 body and installed the 2.2-litre 20-valve AAN turbo five. Official Audi heritage figures give 230PS and 350Nm on overboost, with a top speed of 244km/h. The result looked close to an ordinary Audi 100 but delivered the traction and pace expected of a serious performance car.
Saloon and Avant
The S4 was offered as both saloon and Avant. Audi records 9,286 five-cylinder saloons and 4,654 five-cylinder Avants before the 1994 name change. The Avant is especially important because it helped normalise the fast Audi estate well before the RS2 and later RS6.
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Five-cylinder or V8?
The AAN five-cylinder is the version most closely connected to Audi’s quattro heritage, but selected markets also received a 4.2-litre V8 S4. The two cars have different characters: the turbo five brings boost and the signature off-beat note; the V8 delivers smoother, more immediate torque. Both use the same discreet C4 performance-saloon idea.
Why it became the S6
When Audi renamed the facelifted Audi 100 as the A6 in 1994, the S4 became the S6. This means “C4 S4” and “C4 S6” describe closely related cars, whereas the later B5 S4 is a smaller model with a different platform and twin-turbo V6.
Durability and preservation
The C4 earned a reputation for structural solidity, but age, neglect and tuning still matter. Correct diagnosis should cover boost control, cooling, ignition, fuel delivery, gearbox and differential operation, suspension wear, brake condition and electrical equipment. Original interior trim and model-specific exterior parts can be harder to source than routine service items.
Why the C4 S4 matters
It established a theme Audi would repeat: understated styling, all-weather speed and real long-distance usefulness. It also linked the S2 era with the later S6 and RS estates. The car’s importance is easy to miss precisely because it avoids visual drama.
Frequently asked questions
When was the first Audi S4 launched?
The C4 Audi S4 saloon launched in 1991, with the Avant following shortly afterwards.
What engine does the C4 S4 use?
The principal engine is the 2.2-litre 20-valve AAN turbo five producing 230PS. A 4.2-litre V8 was also offered in some markets.
Why did the S4 become the S6?
Audi renamed the facelifted Audi 100 as the A6 in 1994, so the performance version changed from S4 to S6.
Is the C4 S4 related to the B5 S4?
Only by badge philosophy. The B5 is smaller and uses a different platform and twin-turbo V6.
Was the original S4 available as an estate?
Yes. Audi produced the C4 S4 Avant alongside the saloon.
Research sources
- Audi MediaCenter: 30 years of the Audi S4
- Audi MediaCenter: five-cylinder engine history
- Wikimedia Commons records linked beneath each photograph.
Continue the Audi story
Browse the Rare & Performance Audi hub for more model histories, engineering stories and connected guides.
