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Yes, the rear crossmember, and the front crossmember, are made from steel, not galvanized, with a poor black paint job. This is true for many VWs, Audis, and Porsches. Not sure why they feature a fully galvanized body-shell, and then cheap-out on the paint used for the steel parts nobody sees.....or they should make these parts out of aluminum.
Funny you mention this, today I bought some Extend Rust treatment to address the surface rust already starting on the rear subframe of my 2019 Macan.
I replaced my steel front cross-brace with an aftermarket aluminum (black anodized) one....
That post showed up on my IG feed too. Pretty concerning for folks living in snow country. I wonder if undercoating would help the problem? I had been thinking about getting a Macan at some point, but that post is really making me think twice. That much rust in six years is just crazy.
That photo is really scary. Wonder what sort of life that car lived. Presumably the owner drove the car a lot on salted or brined roads and did not rinse the underbody afterwards. I believe the Cayenne uses a steel rear subframe or cross member too though, as do many other vehicles, so that issue is not unique to the Macan. Maybe Porsche used cheaper paint on this part though.
It seems to me that this sort of failure should be covered by Porsche for many years under the factory corrosion protection warranty, but I will admit that I have not read that warranty so I don't know for sure. One preventive option would be to pull the cross brace off the car before exposing it to harsh road conditions, and have it coated with a more durable coating than the OE paint. Expensive, but not impossible.
It could also be the case that the design of this part allows the corrosive salt water to sit inside of the part because it is hollow and open to water ingress in certain places. It does have holes in the bottom in a few places too, but once the salt makes its way inside the part, I would expect it to stay there until someone goes in there to flush it out aggressively with fresh water and then drive the car to let everything dry out. That does not seem like a practical expectation for someone who lives in a place where it is necessary to drive on salted roads on a regular basis. I think Porsche should have used a difference design to avoid this problem.
Updated post:
Maybe the corrosion warranty doesn't cover this after all. There is some discussion of this (including the warranty as described in certain posts), with some additional photos of another Macan that had rust issues: link
Last edited by Shandingo; Dec 2, 2022 at 11:07 AM.
The corrosion warranty only covers corrosion perforation of body panels.
Yep, that is what the other posts I linked to concluded. I didn't read my warranty, so you are one step ahead of me. I do not plan to drive my car in the salt if I can avoid it, and if I do it will be very infrequently. It does suck though that Porsche doesn't choose to use better designs/materials that are sufficient to allow owners to use their expensive SUVs year round in harsh conditions without being concerns about this sort of thing. The car was not cheap to buy.
Rear crossmembers rusting?
