The 2005 Audi S4 is a high-performance sport sedan (also sold as an Avant wagon and Cabriolet) that blends understated luxury with serious V8 power. It sits in the B6-generation S4 lineup, positioned above the A4 as a more aggressive, premium daily driver with stronger acceleration and upgraded brakes and suspension. This model is ideal for drivers who want quattro all-wheel-drive confidence, a refined interior, and a true performance feel without moving up to a larger executive sedan. In today’s market, it’s often cross-shopped with the BMW 330i/325i and Mercedes C-Class of the era, but stands out for its V8 character and all-weather traction.

- 4.2L V8 performance: The 2005 S4 is powered by a naturally aspirated 4.2-liter V8 (BHF) producing around 340 hp, delivering strong midrange pull and a distinctive V8 sound. - Quattro all-wheel drive: Audi’s quattro system is a core selling point, offering confident traction in rain and snow and a planted feel at speed. - Transmission choices: Buyers could choose a 6-speed manual or a 6-speed automatic (Tiptronic), with the manual typically favored by enthusiasts for engagement and long-term driving satisfaction. - Sport-focused chassis upgrades: Compared to an A4, the S4 includes firmer suspension tuning, bigger brakes, and performance-oriented wheels/tires for sharper handling. - Premium interior and build: Supportive sport seats, high-quality materials, and available features like upgraded audio and convenience options help the 2005 S4 feel upscale even by modern standards.

Shoppers researching 2005 Audi S4 reliability should know this is a rewarding car when maintained properly, but it can be costly if neglected. Here are several 2005 Audi S4 problems and common issues reported by owners: - Timing chain tensioner/guide wear (rear-mounted timing system): A well-known concern on the 4.2L V8. Rattling on cold start can be a warning sign. Issues are often discussed around 80,000–120,000 miles, and repairs can be expensive due to the chain system’s location. - Coil packs and ignition misfires: Misfires under load, rough idle, or check-engine lights are commonly tied to aging coil packs and spark plugs. This can show up anywhere from 60,000 miles onward depending on maintenance and heat exposure. - Oil leaks and consumption: Valve cover gasket leaks and other seepage points can appear with age, and some cars consume oil. Regular oil level checks are important, especially on higher-mileage examples. - Control arm and front suspension wear: Clunks over bumps, vague steering feel, and uneven tire wear can be linked to worn control arm bushings/ball joints, often appearing around 70,000–120,000 miles depending on road conditions.