Command attention from every angle with the Big Fin Carbon Fiber Rear Diffuser for the F80 M3 and F82 M4. Designed for drivers who want a more aggressive rear profile, this diffuser features deep vertical fins, sharp angles, and a wide center channel for true motorsport presence. Built to match OEM bumper contours, it’s the perfect combination of aggressive styling and clean fitment.

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Key Features

• Big Fin design with deep vertical fins and wide center cutout

• Constructed from real carbon fiber with a 2x2 twill weave pattern

• Designed for flush fitment on OEM rear bumper

• UV-resistant gloss finish for long-term clarity and durability

• Matte and forged carbon options available upon request

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Compatible Models

• BMW F80 M3 (2015–2018, Sedan)

• BMW F82 M4 (2015–2020, Coupe)

• BMW F83 M4 (2015–2020, Convertible)

Designed to fit factory rear bumper. Not compatible with aftermarket setups.

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What’s Included

• (1) Big Fin Carbon Fiber Rear Diffuser

• Tabs or mounting extensions (may vary by batch)

• Installation hardware not included on most products

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Why Buy From Eterna Motorworks

Eterna Motorworks is the standard in premium aftermarket automotive parts and services. With over a decade of hands-on experience, we’ve earned the trust of enthusiasts and professional builders worldwide by delivering unmatched quality, precision fitment, and long-term credibility. Every part and service we offer is curated to meet the highest expectations in styling, performance, and reliability — both on the road and in the shop.

If you’re searching for a trusted partner to set your build apart — welcome to the team.

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Professional installation is highly recommended.

Installation hardware not included on most products.

For full fitment, installation, and store policy details, please refer to our policies before purchasing.

Worldwide shipping available upon request.

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Your next mod starts here. Upgrade your build the right way with Eterna Motorworks.