 The GL450 has so many problems, that dealers across the country and head quarters do not know how to fix, the customer frequently hears "we have no idea what is wrong or how to fix your problem."  I had a Lexus LX 470 and as soon as I can get the Mercedes out of the shop, they have had it for 9 days, I am headed for Lexus and trading it in.   The vehicle backfires on every cold start, a very dangerous situations.  "Nothing but the best, the safest, technologically advanced;" far from it.   Mercedes you are better than this.   Step up your game and your customer service response.  I was told today by Mercedes corporate customer care group "they  had no idea when they would have an answer or solution to the backfire problem.  When I said do you think you will know something by December, the regional claims manager stated "I have no idea."  "Nothing but the best?" I will never recommend or buy another Mercedes.