Audi A5 S-Line / S5 B9 Carbon Fiber Rear Diffuser – Prepreg Dry Carbon (2017–2019 Sportback)

2017–2019 Audi A5 S-Line / S5 B9 Sportback Rear Diffuser – Pre-Preg Dry Carbon Fiber

Give the rear end of your Audi A5 S-Line or S5 B9 Sportback a sharper, more aggressive finish with this pre-preg dry carbon fiber rear diffuser. Precision-molded to follow the factory bumper lines, it adds depth and contrast for a true performance-inspired presence while keeping a refined factory look.

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 exceptional strength, consistent weave, and a lighter finished component than standard wet carbon
• Manufacturing: Autoclave cured, precision 3D-designed and CNC moulded for accurate fitment
• Surface finish: Deep high-gloss clear coat that showcases the 3K twill weave and provides long-term UV protection
• Configuration: Single-piece diffuser for the lower rear bumper

Design & Aerodynamics

• Aggressive stance: Diffuser profile adds depth and visual weight to the lower rear for a more planted, performance-focused 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

• 2017–2019 Audi A5 S-Line B9 Sportback
• 2017–2019 Audi S5 B9 Sportback
• Fits the A5 S-Line and S5 factory rear bumper only — not compatible with the standard non-S-Line A5 or aftermarket bumpers

Package Contents

• 1 × pre-preg dry carbon fiber rear diffuser
• Adhesive tape and mounting screws for installation

Installation

• Two mounting options: Fits using the included adhesive tape and mounting screws for a secure, long-lasting fit
• Drilling required for screw mount: Screw fixing pierces the bumper, so if you use the screw option this is a permanent modification rather than a reversible fit
• Surface prep: If using adhesive tape, thoroughly clean, degrease, and dry the rear bumper before fitting to ensure maximum adhesion
• Alignment: Dry-fit and check the diffuser sits centred and even across the bumper before committing to either method
• Professional installation recommended for correct positioning, panel alignment, and a clean finish

Before You Install

• Confirm your car is an A5 S-Line or S5 B9 Sportback (2017–2019) before ordering — this will not fit the standard non-S-Line A5
• Screw mounting is permanent — it requires drilling into the bumper, so decide on your method and confirm placement before starting
• Take care when parking rear-in — lower rear panels sit close to kerbs and parking blocks