It's all about balancing your priorities. If your main focus is school and doing well in it, buy a good, reliable daily that will get you to your classes on time, safely and without worrying about whether it's going to break on your way there. I had my first auto loan at 19 and bought a car that I knew was going to be good for me financially and it worked out perfectly for the time I had it that it got me back and forth to my job that was my main priority.
After my divorce I had to refinance my car (which added another year to my loan) and I now have around 3 payments left and look forward to saving that extra $400/mo.