Question about Montblanc Carrier Super Rider+

They might fit, I use it for a Fiat 500x and it fits well. The fixing straps in the middle to the side of the tailgate could be difficult, because the GLC has elements of the rear light there on the tailgate, so there is no conventional sheet metal edge where the U-hooks can be attached. (Picture 14 of the instructions)
Assembly instructions here: https://www.montblancgroup.com/documents...
!! Assembly and adjustment of the position and straps took more than 1h. The rear spoiler on the tailgate should not be pushed downwards by the two upper straps, as this is where the main load of the carrier is.