2014-2020 BMW M3 F80 & M4 F82 KNF Style Rear Diffuser

Enhance the rear profile of your BMW M3 or M4 with this KNF Style carbon fiber rear diffuser with LED light. Designed for the F80 and F82 chassis, this rear aero upgrade adds a bold lower bumper accent while complementing the vehicle’s sporty factory body lines.

The KNF Style design creates greater visual definition across the lower rear bumper area and gives the vehicle a more aggressive, track-inspired exterior presence. Its diffuser profile and integrated LED light add a distinctive rear-end detail that enhances aerodynamic styling and stands out in both daytime and nighttime settings.

Crafted from carbon fiber, this rear diffuser provides a premium exterior accent with a performance-focused appearance. Designed for compatible 2014-2020 BMW M3 F80 and M4 F82 models, each package includes one KNF Style rear diffuser with LED light.

Product Specifications

Key Features

• KNF Style rear diffuser designed for compatible BMW M3 and M4 models
• Compatible with listed F80 and F82 chassis applications
• Integrated LED light adds a distinctive rear-end detail
• Creates a more aggressive lower rear bumper profile
• Adds bold visual definition across the rear diffuser area
• Track-inspired design complements the factory rear bumper lines
• Carbon fiber construction with a premium exterior appearance
• Designed to complement compatible front lips, side skirts, and trunk spoilers
• Suitable for sedan and coupe exterior builds
• Includes one KNF Style rear diffuser with LED light

Package Includes

• One rear diffuser with LED light

Note: Brackets, clips, screws, double-sided tape, automotive adhesive, wiring accessories, control modules, and additional mounting hardware may not be included unless otherwise specified. LED wiring should be completed by a qualified installer.

Installation

• Designed for installation along the compatible lower factory rear bumper
• Professional installation is recommended for accurate alignment, secure mounting, and LED wiring
• Test fit the diffuser before drilling, trimming, applying adhesive, wiring the LED light, or completing final installation
• Clean and degrease all mounting surfaces thoroughly before installation
• Use suitable automotive screws, clips, brackets, or adhesive as required
• Additional mounting hardware, wiring accessories, or supporting brackets may be necessary
• Minor drilling, trimming, sanding, wiring, or alignment adjustment may be required
• Confirm adequate clearance around the exhaust outlets and surrounding bumper components
• Test LED function and verify secure attachment before driving

Fitment

• 2014-2020 BMW M3 Sedan F80
• 2014-2020 BMW M4 Coupe F82

United States: Free shipping available to the lower 48 states across all items. Other states will incur a shipping charge.

Worldwide: Free shipping is available for Complete Headlights, Taillights, DRLs. For custom headlight retrofits, carbon fiber products, and performance products, there will be a shipping charge.  

Please note:
• For Retrofits, you are purchasing a headlight modification service.
• If you select "Shipping own headlights to BayOptiks for modification", you are required to send us your headlights.
• If you choose "Purchase new OEM headlights", we will order and modify a new OEM headlight for you.
• Once your customizations are complete, we will ship it to you!

• Complete Headlights: 3-5 business days for order processing plus shipping time.
• Custom & Pre-Built Headlights: 6-8 weeks depending on the complexity and component availability.
• New OEM and cores: 6-8 weeks plus an additional 4-8 weeks as these are special orders base on the vehicle VIN due to different versions (North American, European, etc.)
• DRLs, Taillights, Brake Pads, and Carbon Fiber Aero: 3-5 business days for order processing, plus shipping time.
• Lens Replacements: 1-3 weeks plus shipping time.

Please note, we do not have control over the time frames of our vendors, manufacturers, and delivery services as they may delay processes in regards to components and shipment.