So the guy really wants a MBP and he is willing to make sacrifices to get it. I would not have gotten my college degrees without my laptops and when I purchased my MBP, I made massive financial sacrifices. Without my MBP, I would have never reached advanced degrees as I have severe learning and moderate physical disabilities; I cannot write cursive at all, I print so poorly that it is illegible, and I cannot process and understand information when all of my focus is on trying to write it as neat as possible.
If anything, that speaks to the quality of the OP's character by showing determination. I don't have a car currently; I walk, bike, occasionally hitchhike, and use public transportation (I live in a big city tho), and in the process I save thousands of dollars each year. I try to give some of that money to a local charity that provides poor-as-hell students with computers and other educational equipment that they cannot afford; I often buy used laptops from people I know and donate them as well. I was in the situation myself not very long ago and someone who cared about me assisted me in realizing my dreams. Everyone says 'get an education', but if you are too poor to afford some form of a computer, you are screwed in so many ways no matter how smart and capable you may be. Cars are a money-pit and depending on your location and your life, you may or may not be able to function without one.
If you are financially able to afford both a reliable automobile and a new MBP, give thanks as not everyone is as fortunate as you. (Please don't misconstrue that as 'you have it easy' or 'you have it all handed to you'; most people who can afford both work their butts off for everything they have and they absolutely deserve it. With that said, people who have both may not be able to understand the dynamics of living near poverty or on a very restricted income.
If you haven't already, consider donating your old laptops to educational causes. If you are really in the Christmas spirit, give someone who means a lot to you a new laptop whom you know that they cannot afford on it their own (you can get them as cheap as $300 pretty regularly). If you are feeling super jolly, give that college student you love a 13 inch MBP; they really are the 'rave' on campuses and I would say that they are one of the best education tools since the pen. I've had a gazillion people tell me something along the lines of 'I love your computer, they are so amazing/cool/fast/reliable/etc, I wish I could afford one but no matter how much I work I can't, I'd do nearly anything to get one'. I wish I had the money to buy every college student a MBP.