Diffusers
77 products
Carbon fiber rear diffusers led by the BMW G80 M3 and G82/G83 M4, with bumper corners and trims to match. For a G80 M3 diffuser, the two main choices are the MP-style dry carbon diffuser, which replaces the factory plastic part on its own clips, and Unit 17’s 3-piece design with rear corner extensions.
You’ll also find diffusers for the G87 M2, X3M and X4M, M5, X5M and 3, 4 and 5 Series, plus the Audi RS3, RS6 Avant, S3 and S5, the Mercedes C63 and C43, and the 2024 Tesla Model Y Long Range. Current-model diffusers are mostly pre-preg dry carbon; many older listings say carbon fiber without naming the process.
Diffusers buying guide
G80 M3 and G82 M4: diffuser, corners and outer trim
The rear of a G8X has three areas you can change. The center diffuser: the MP-style diffuser bolts on with the OEM hardware and clip locations, while our 3-piece version adds rear corner extensions and uses the factory mounting points. The outer trim: a carbon piece replaces the gloss-black surround and works with the OEM diffuser or selected aftermarket ones. The corners: carbon replacements for the gloss-black corner pieces, with or without winglets, in separate M3 and M4 versions. Unit 17 also makes its own G80 and G82 corner extensions. Shop by car under G80 M3 diffusers or G82/G83 M4 diffusers.
G87 M2 choices
Our 3-piece G87 diffuser wraps around the exhausts to keep a low line across the bumper and reuses the OEM hardware with no drilling. There is also a one-piece dry carbon diffuser that needs no drilling, and a CS-style diffuser that bolts to the factory points and comes in a matte or gloss clear coat. For smaller changes, the add-on rear bumper splitter covers the gloss-black trim over the bumper vent, with a cut-out for the parking sensor and 3M tape already applied. See the G87 M2 diffusers.
X3M, X4M, M5 and older models: what to check
- The SQ-style diffusers for the X3M and X4M are listed for LCI (2022 on) cars. The X4M version is also sold with a built-in brake light and a plug-and-play harness.
- The SOOQOO 3-piece for the X3M LCI isn't compatible with the factory tow hitch.
- The Unit 17 X3M 3-piece with corner splitters fits pre-LCI and LCI cars but not the X4M.
- The 3D-style 3-piece for the F90 M5 LCI needs the rear bumper removed.
- Several F30, F32 and F10 diffusers are cut for a particular exhaust layout and M Sport bumper, and the big-fin W204 C63 diffuser fits the coupe and sedan, not the wagon.
Clips, bolts or drilling
Most current-model diffusers mount to the factory points. Older listings usually arrive pre-drilled with self-tapping screws and say drilling is required, so plan on a shop. Diffusers with an F1-style brake light need wiring, and the G80/G82 version needs the bumper off to do it. Test-fit before painting or drilling.
Frequently asked questions
Does a G80 M3 diffuser fit the G82 M4?
The center diffusers usually do: the MP-style diffuser, the outer trim and our 3-piece diffuser are listed for the G80, G82 and G83, and the 3-piece asks you to pick M3 or M4. The rear corner pieces are different, so buy the M3 or M4 version to match your car.
Do I need to remove the rear bumper to fit a diffuser?
Not for the G8X MP-style diffuser, which uses the OEM hardware and clip locations. You do for the G80/G82 diffuser with the F1-style light, to wire the LED and release the factory clips safely, for the 3D-style F90 M5 LCI diffuser, and for the Brabus-style W205 C63 coupe diffuser, whose factory part is riveted to the bumper.
Should I choose rear corners with or without winglets?
Choose winglets for the M Performance look, with a small fin at each corner of the bumper. The versions without winglets keep the factory corner shape in carbon, a good option if you like the stock profile but not the gloss black. Either way, buy the M3 or M4 version; they replace the factory gloss-black pieces, which are held by clips and tabs.
Will a carbon diffuser work with my tow hitch or parking sensors?
Check the listing. The SOOQOO X3M LCI diffuser is not compatible with the factory tow hitch. The X5M F95 set reuses the factory parking-sensor carriers, which move over from the old diffuser, and the G87 bumper splitter has a cut-out for the sensor. If your car has either option, text 609-525-4865 before ordering.
Which diffusers are designed by Unit 17?
The G80/G82 3-piece diffuser, the G80 and G82 rear corner extensions, the G80/G82 diffuser with an F1-style brake light (coming soon), the G87 M2 3-piece, the X3M 3-piece with corner splitters (coming soon) and the RD1 Pro for the Audi RS3 facelift. They are sold only here. See all Unit 17 exclusives.