AutoCarbon Carbon Fiber Rear Diffuser for BMW M3


What better way to complete the look of the M3′s rear than with a carbon diffuser.    It gives an aggressive look to an otherwise tame back-end.

In the case of the E92 M3, it really accentuates the quad exhaust and goes great with the other carbon fiber accessories on the car.

These diffusers are available for many BMW models at



Flawless carbon fiber finish.


Great design.


Start by removing the two screws under the bumper holding the bumper to the vehicle.


(To show where we are working)


Fit the spoiler in place roughly.  The spoiler will not be in the exact final place yet, but reinsert the screws back into the bottom of the car.  Dont tighten these screws fully yet as we need some play to shift the location of the diffuser a bit in either direction.


This is how it looks under the car, with the diffuser bolted in place.


On each end, position the diffuser so that it is in the correct position.  Ensure that both of the screw holes in the diffuser have bumper trim behind them where they can be secured.    Even though the diffuser is rigid, it does have some flex in it, so if you need to twist / bend it a little to make it get into the exactly correct position on both sides, this is no problem.   When positioned correctly, use a drill to drill two tiny pilot holes in the bumper through the holes that are already in the diffuser.



Use 4 stainless screws to secure this to your bumper through the holes you just drilled.


Looks awesome!

What an aggressive stance… better pictures to follow