I wish Merc would go back to the older style raised roof-rails. They are easier and much quicker to fit roof rails to, and give loads of options for tie-down.
I've tried both Thule and OEM bars on my GLC, both have their good and not so good points, neither are as practical as the setup I had on my W204 Wagon - the standard raised rails with Thule aerobars.
As for drilling the rails, I'd not go there.
Last edited by Neil_t; 11-01-2019 at 05:09 PM.