I am 20 years old and getting a 135i, and don't see anything wrong with it. No, my parents are not spending a dime on the car, insurance, or even gas. Got one free year of car insurance and that's it. The rest I have payed on my own. Still live at home which is one benefit. Will still be saving money on the side for a house I plan to buy before 28.
Would it be easier to continue to drive my POS for the next 8 years and get a house a little earlier? Sure, but you only live once and I have thought about a new car for the past 4 1/2 years now.
Can't wait for March.