* Engine: The A4 typically offers a range of four-cylinder and six-cylinder engines, prioritizing fuel efficiency and smooth power delivery. The S4 boasts a significantly more powerful, high-performance V6 engine, usually turbocharged. This results in considerably more horsepower and torque.
* Performance: The S4 is tuned for a sportier driving experience. This includes things like a firmer suspension, more responsive steering, and upgraded brakes capable of handling higher speeds and aggressive driving. The A4's suspension and handling are more focused on comfort.
* Exterior Styling: While subtle, the S4 has visual cues that distinguish it from the A4. These typically include more aggressive bumpers, side skirts, a unique grille design, and possibly larger wheels and sportier exhaust tips.
* Interior Features: While both offer luxurious interiors, the S4 may include sportier seats (often with more bolstering for better lateral support), unique interior trim, and potentially different instrument clusters showcasing performance data.
* Price: The S4 is considerably more expensive than the A4, reflecting its enhanced performance capabilities and features.
In short: The A4 is a comfortable, refined luxury sedan, while the S4 is a performance-oriented luxury sedan offering significantly more power and a sportier driving experience. They share a similar platform and many design elements, but the S4 is a clear step up in performance and price.
