Rear bumper holes

It is an aero thing indeed. Though I do like the "japanese racer" look of it too As for the weight saving, there is a good deal too. Inside of rear bumper is a fairly bulky beam consisting of a metal rail and dense plastic crash absorbent. Here's a picture:



According to my old notes the beam weights 5.2 kg. If you look at the photo you'll notice four studs on each side of the beam, these mount the bumper assembly to the body. With beam removed, you'll be left with outer bumper skin only and will have to come up with other means of affixing it to the car. I've bolted it to the rear number panel with some reinforcement to spread the load.

There are also rear tow hooks (aka baby teeth), bolted to rear chassis near the bumper structure.



Altogether they weight 1.4 kg so another good saving here. I've put a single tow strap instead to still have something to hook up at for when I run out of talent on track. It added a few hundred grams back but a kilo still saved.

It's obvious, but still worth pointing out: with the beam removed you won't have any crash energy absorbent there and any rear end contact will easily bend/crush the bumper and go into rear chassis.

Moro thanks for the replies, great info and exactly what I wanted to know. What did you use to cut the holes, a hole saw?

7kg saved is well worth it, car is only used on track days so fingers crossed rear impact protection won't be needed.

If it's only used on track you could get away with trimming the entire bumper to half size or even removing it completely and seeing if you notice a difference. It's often described as a parachute.