The price of insurance and tires are what's really going to hit you hard. Correct me if I'm wrong, but I think you said you were 16. When I first got my XF, I was 18 and insurance for me was around $2400/year, and that's with $1000 deductibles on collision and comprehensive, and multi-car/multi-residence discounts. I wasn't a bad driver, had no tickets on my record. It's been 2 years and I still pay around $1800/year for insurance. Tires cost at least $800 for all 4, and that's if you can find them REALLY cheap. My last set of all-seasons cost just under $1000, and they've only lasted a year and half (and they're in terrible shape right now). Repairs, if you buy one without a warranty, can kill you. I just had to order a new windshield shroud under warranty- it cost the dealer $2300 just for 3 plastic pieces that go around the windshield. Oil changes, if you have them done at the dealer, will cost you around $140 each. For those older than you and me, with steady careers, taking care of this car is just taking care of their weekend toy. For me, it's a daily driver, since I can't afford to have a second car (a beater). I actually had to sell my beater so I could put new tires on the XF.

Don't let me scare you. If mom and dad are helping you out (which they most likely are), you're a very responsible 16-year-old guy, and you take good care of the car, then this could be an affordable prospect for you. I know I don't regret getting mine (I got mine for my birthday too). Just remember what this car is- one of a kind. Also remember that those body parts are impossible to get right now, and almost anything mechanical or electrical is going to be Mercedes-Benz.