FRP Rear Bumper Diffuser for 2009–2012 Audi S4 B8 Sedan

Designed for selected 2009–2012 Audi S4 B8 Sedan models, this FRP rear bumper diffuser replaces the factory lower rear diffuser and gives the pre-facelift S4 rear bumper a cleaner, more defined appearance.

This page is specifically for the FRP version of the Audi S4 B8 rear diffuser. It is intended for customers who prefer a gloss black or matte black exterior finish rather than exposed carbon fiber.

Vehicle Fitment

Vehicle: Audi S4
Generation: B8 Pre-Facelift
Model Years: 2009–2012
Body Style: Sedan
Product Type: Rear Bumper Diffuser

Not intended for Audi A4 B8 Base or A4 S line rear bumpers. Rear bumper designs vary between A4 and S4 configurations, so please confirm your bumper style before ordering.

If you are unsure about compatibility, send us your vehicle year together with clear rear bumper photos so we can help review fitment before purchase.

Gloss Black or Matte Black FRP

The diffuser is available in Gloss Black FRP and Matte Black FRP options. FRP provides an alternative to exposed carbon fiber for owners who want a black rear diffuser finish while keeping the S4 B8 rear bumper styling clearly defined.

Choose the finish according to the appearance of your vehicle and other exterior trim. Gloss black creates a more reflective finish, while matte black provides a more understated look.

Replacement-Style Rear Diffuser

This is a replacement-style rear bumper diffuser designed to take the place of the factory lower diffuser rather than simply attach over the original part.

The product is intended primarily as an exterior styling upgrade. No specific downforce, drag reduction or handling improvement is claimed without product-specific aerodynamic testing.

Installation

Installation requires removal of the original lower rear diffuser before fitting the FRP replacement. Test-fit the product before final installation and confirm that the mounting points, bumper edges and exhaust openings align correctly.

Professional installation is recommended if you are unfamiliar with rear bumper trim removal or panel alignment.

Confirm Fitment Before Ordering

This product is specifically positioned for the 2009–2012 Audi S4 B8 pre-facelift Sedan. Do not select it based only on the Audi A4/S4 model family name, as A4 Base, A4 S line and later B8.5 rear bumper designs may use different diffuser shapes.