2018–2019 Audi S4 B9 Carbon Fiber Rear Diffuser Video

See the carbon fiber rear bumper diffuser installed on an Audi S4 B9 Sedan and review the overall shape, carbon fiber finish and rear bumper appearance before ordering.

Designed for selected 2018–2019 Audi S4 B9 Sedans, this carbon fiber rear bumper diffuser replaces the corresponding factory lower rear bumper section with an exposed-carbon exterior upgrade. Its vehicle-specific profile follows the shape of the S4 rear bumper while giving the lower rear section a more defined and distinctive appearance.

This product is intended specifically for compatible Audi S4 B9 Sedan applications. This product is designed for compatible Audi S4 B9 Sedan rear bumpers and is not intended for Audi A4 Base or S line applications.

Vehicle Fitment

Make: Audi
Model: S4
Years: 2018–2019
Generation: B9 / Pre-Facelift
Body Style: Sedan 4-Door
Product Type: Rear Bumper Diffuser
Material: Carbon Fiber
Installation: Replacement Style

This rear diffuser is intended for selected 2018–2019 Audi S4 B9 Sedan applications. Rear bumper and exhaust configurations should be checked before ordering, especially if the vehicle has aftermarket exhaust components or previous bumper modifications.

Carbon Fiber Rear Diffuser Design

The exposed carbon fiber surface adds a contrasting finish across the lower rear bumper area while maintaining the overall proportions of the S4 B9 bodywork. The diffuser shape is designed around the S4 rear bumper rather than serving as a universal rear lip or add-on trim piece.

Customers searching for an Audi S4 B9 carbon fiber rear diffuser or S4 Sedan rear bumper diffuser should confirm that their vehicle matches the listed 2018–2019 S4 Sedan application before purchase.

Replacement-Style Installation

This product is designed as a replacement-style rear bumper diffuser component rather than an adhesive overlay. Installation requires removal of the original lower rear bumper section and alignment of the replacement diffuser with the factory bumper area.

Professional installation is recommended. Mounting requirements can vary depending on vehicle condition, existing hardware and previous modifications, so test-fitting the diffuser before final installation is advised.

Fitment Check Before Ordering

If you are unsure whether this carbon fiber rear bumper diffuser matches your Audi S4, send us the vehicle year and clear photos of the rear bumper and exhaust area. We can help compare the bumper configuration before purchase.

Explore More Audi S4 Carbon Fiber Parts

Browse more Audi A4 / S4 B9 carbon fiber parts, explore the wider Audi A4 / S4 collection, or view more Audi carbon fiber parts from AHACARBON.