Audi A4 B9 S-Line / S4 Rear Diffuser – Prepreg Dry Carbon Fiber (2020–2022 Sedan)

2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber

Give the rear end of your Audi A4 S-Line or S4 B9 the same attention as the front with this pre-preg dry carbon fiber rear diffuser. Molded to the factory rear bumper lines, it adds depth and sharp edges for a refined, motorsport-inspired presence without going over the top.

Build

• Material: Pre-preg dry carbon fiber in a 3K twill weave — the resin is pre-impregnated into the weave under controlled conditions before autoclave curing, giving superior strength while keeping weight to a minimum, a consistent weave, and a lighter finished component than standard wet carbon
• Manufacturing: Autoclave cured, precision 3D-moulded for accurate fitment
• Surface finish: Deep high-gloss black clear coat that highlights the 3K twill weave and provides long-lasting surface protection
• Configuration: Single-piece diffuser for the lower rear bumper

Design & Aerodynamics

• Aggressive stance: Diffuser profile adds depth and sharp lower-rear edges for a more planted, motorsport-inspired rear end
• Carbon aesthetic: Refined 3K twill dry carbon weave and high-gloss clear coat deliver premium contrast against the factory paint
• Factory-style integration: Precision-molded to the contours of the factory rear bumper for a clean, seamless fit

Fitment

• 2020–2022 Audi A4 S-Line B9 Sedan
• 2020–2022 Audi S4 B9 Sedan
• Fits the A4 S-Line and S4 factory rear bumper only — not compatible with the standard non-S-Line A4 or aftermarket bumpers

Package Contents

• 1 × pre-preg dry carbon fiber rear diffuser
• Mounting screws for installation

Installation

• Screw-mounted: Secures with the included mounting screws for a secure, rattle-free fit
• Drilling required: Screw fixing pierces the bumper, so this is a permanent modification rather than a reversible fit
• Surface prep: Clean and degrease the rear bumper at the fixing locations before installation
• Alignment: Dry-fit and check the diffuser sits centred and even across the bumper before driving any screws
• Professional installation recommended for correct positioning, panel alignment, and a clean finish

Before You Install

• Confirm your car is an A4 S-Line or S4 B9 Sedan (2020–2022) before ordering — this will not fit the standard non-S-Line A4
• This is a permanent, screw-mounted fitment — dry-fit and confirm placement carefully before driving any screws, as holes cannot be undone
• Take care when parking rear-in — lower rear panels sit close to kerbs and parking blocks