Seats in some 2015 Mercedes-Benz C-class sedans releasing waxy chemical substance

There's a lot to like about the new C-class and its comfortable interior, but defective seat material isn't really at the top of our list.PHOTO BY MERCEDES-BENZ

Benz says it’s aware of the problem; replacement parts on the way

    We’ve been just about unequivocal in our praise of the new 2015 Mercedes-Benz C-class sedan, especially when it comes to the very pleasant interior. So it’s only fair to report on problems when they arise, like the odd waxy/oily substance some C-class owners claim is seeping out of the seats of their new cars.

    You can find details, photos and speculation about the cause of the problem at the mbworld.org forums. We’re not sure what causes the bleeding, but it’s only impacting cars equipped with MBTex synthetic surfaces -- and a highly unscientific poll suggests that it may only impact North American market cars, which are built at Benz’s Tuscaloosa, Ala., plant.

    Further, the problem seems to appear (or perhaps intensify) in extremely cold weather; warming up a car that’s been sitting outside in frigid temperatures seems to trigger the blotches. They can be wiped away with warm, soapy water, but may (or may not) return.

Here's an example of what some C-class owners are reporting.PHOTO BY MBWORLD.ORG FORUM POSTER STANNH

    Some owners speculate that the substance emerging from the seats is a plasticizer/softening agent, suggesting that the batch of MBTex that made its way onto these particular cars is defective. That seems reasonable, but again, it’s all speculation at this point.

    We asked Mercedes-Benz if they were aware of the problem, and they got back to us with this statement:

    Daimler AG became aware that, in a small number of individual cases, it is possible for temporary spots and/or shiny patches to form on the man-made leather surfaces of the 2015 C-class in sub-freezing temperatures. No accidents or injuries have been reported, and we have no reason to believe that there are any hazards to customers. Replacement parts are expected to start shipping to dealers by next week.

    A Mercedes-Benz technical service bulletin posted to the mbworld forum claims that some sort of “spare parts kit” -- which might include replacement of some or all of the affected seat surfaces -- is in the works. If you’re encountering this problem in your new C-class, your best bet is to contact your friendly neighborhood authorized Mercedes-Benz dealership about the fix. And maybe throw a cover over those seats in the meantime.