I purchased three Mercedes in 2018: 2018 S63, 2011 SLS, and 2019 G63 (which is sitting at port due to Fed furlough/still haven't taken possession) with my AMEX Mercedes Platinum in full. The reason I did it is because you can get 5x points, so I quickly got close to 3 million points.

With all that being said, it cost me 3% to pay the dealer to process it each time, which at 5x, I still win. I don't know why you would on a normal platinum- the 3% fee wouldn't offset a G-Wagon 1.5x points rebate + 35% MR back.

They discontinued Mercedes Platinum on Jan 11 of this year probably because of me or people like me.