The G8X's rear bumper does a lot of work visually, and then the diffuser underneath it is painted plastic with four exhaust tips that aren't.
A Feral Auto design built from autoclaved 2x2 pre-preg dry carbon fiber, shaped to the factory rear bumper and sized to fit the G80 M3, G82 M4 and G83 M4 Convertible alike.
The four exhaust cutouts are the hard part. They have to clear the factory tips with an even gap on all four, and the fin that runs between each pair is where a hand-laid part usually shows a thick, resin-rich edge.
Closes the car against the Carbon Fiber Front Spoiler at the other end, and reads as one set with the Carbon Fiber Mirror Covers in the same weave.
It isn't part of the Carbon Front End Bundle Kit, which covers the front of the car only — the diffuser is bought on its own.
Fits the 2021-2027 BMW M3 (G80) Sedan, M4 (G82) Coupe and M4 (G83) Convertible.
Why Autoclave Pre-Preg Dry Carbon Fiber
Pre-preg carbon arrives with the resin already impregnated into the weave at a controlled ratio, so no resin is added by hand during layup — that is what makes it dry carbon. Curing it under heat and pressure in an autoclave consolidates the laminate and drives out trapped air that would otherwise show as flaws in the finished surface. Other processes introduce the resin at the mold, so the ratio is set during layup rather than before it.
A diffuser is all fins, channels and inside corners. Those are exactly the geometries where hand-laid resin pools and cures thick, and where an autoclaved laminate keeps the weave consistent from the face of a fin down into the valley beside it.
Please note: Matte and Forged Carbon finishes are non-refundable once the order has been placed.
Browse the full BMW G8X M3/M4 collection.
Free standard shipping on all orders delivered within the 48 contiguous United States.
In-stock parts are prepared for shipment within 1–3 business days. If a part is not currently in stock, the lead time shown under the Add to Cart button applies. Once a shipment leaves our facility, most orders arrive within 3–7 business days, and freight shipments within 5–10 business days.
We also ship to Alaska, Hawaii, U.S. territories, APO/FPO/DPO addresses and internationally by quote — contact us before ordering. Full details in our Shipping policy.
Returns require our approval. Contact us within 5 days of receiving your item to request one. Approved returns are subject to a 30% restocking fee plus return shipping, and original shipping is non-refundable.
Items that have been installed, used or modified cannot be returned. Non-standard carbon finishes are non-returnable once the order has been placed.
If we shipped the wrong part or it has a manufacturing defect, there is no fee and we cover return shipping. Damage in transit must be reported within 24 hours of delivery — see our Shipping policy. Carbon components carry a 6-month structural and finish warranty. Full details in our Refund policy.
