The 2015 Audi S4 is a compact luxury sport sedan that blends daily comfort with serious performance, making it a strong pick for drivers who want one car that can commute, road trip, and still feel quick on a back road. It sits above the A4 in Audi’s lineup with a more powerful engine, sport-tuned hardware, and upscale standard equipment. This model is part of the B8.5 generation (2013–2016 facelift), known for its sharp styling updates and refined technology. In the used market, the 2015 S4 is often cross-shopped with the BMW 335i and Mercedes-Benz C450/C43 alternatives for its balance of speed, all-weather traction, and interior quality.

- 3.0L supercharged V6 (TFSI) with 333 hp and 325 lb-ft of torque, delivering strong midrange pull and quick passing power. - Choice of transmissions: 6-speed manual or 7-speed S tronic dual-clutch automatic, with many buyers favoring the fast-shifting S tronic for daily driving. - Quattro all-wheel drive for confident traction in rain or snow and strong launches, a key reason many drivers choose the S4 over rear-wheel-drive rivals. - Available sport differential (on many Premium Plus/Prestige builds) for sharper cornering and better power distribution when accelerating out of turns. - Performance-focused options and tech: Drive Select modes, available adaptive damping, and available MMI navigation with Bluetooth and a premium audio setup depending on trim.

Shoppers researching 2015 Audi S4 reliability will find that many examples are solid when maintained well, but there are a few recurring 2015 Audi S4 problems to know before buying. 1) Water pump/thermostat leaks and cooling system issues: A common complaint on the 3.0T engine is coolant seepage from the water pump and/or thermostat housing. Symptoms include a low coolant warning, coolant smell, or visible crusty residue near the front of the engine. This can show up anywhere from about 40,000 to 90,000 miles depending on heat cycles and prior repairs. 2) PCV system and oil consumption-related symptoms: Some owners report PCV valve issues that can cause rough idle, lean codes, or increased oil usage. While not every S4 consumes oil, it’s important to monitor oil level and look for vacuum-related drivability issues, often appearing in the 60,000–100,000 mile range. 3) S tronic (DSG) mechatronic/shift behavior concerns: The 7-speed dual-clutch can develop hesitation, harsh engagement, or warning lights if fluid service is skipped or if the mechatronic unit begins to act up. Many cars are trouble-free, but higher-mileage examples (often 70,000+ miles) are more likely to show shift quality changes, especially in stop-and-go driving. 4) Carbon buildup on intake valves (direct injection): Like many direct-injected engines, the 3.0T can accumulate carbon deposits over time, leading to reduced performance, misfires, or rough idle. Walnut blasting/cleaning is commonly discussed around 60,000–100,000 miles depending on driving style and fuel quality.