There's a lot of different versions of the G. You didn't say if it was new or even if it was the diesel or the G550/G63.
If it is the newer G550/G63 models, know that they take Premium Grade gas. If you're going cross-continent, I wouldn't expect a lot of stations to have that.
I didn't know they made that many things for W463A. Things like the LeTech I was only ever to find being sold on gwagenparts.com, which looks so shady that I didn't want to even have it in my browsing history.