I don't think getting a Maybach for your sweet 16 counts.

He should be given a car which he could drive. I know a couple kids who have Maybach's, Rolls Royces, Limos, and armored Escalades/ Range Rovers, and are younger than 16 (Some older) but they don't count as their cars.
I also know kids between 16-20 who have very expensive cars (some multiple) which are theirs. Youngest I have seen is a 14 year old with a S63 AMG (Won't get into the age )

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2011 ///X5 M (On Order)

2009 X5 4.8 M Sport Space Gray/Black Fully Loaded

2007 GMC Yukon XL Denali Loaded and Customised