18 year old getting a car?

i'm 18 and i just got a job. since i'm in college and getting a grant from college, i was thinking of getting a car. i really want a jeep but a used one go from 13,000- to 28,000 and that's a lot of money to save up. so i was thinking of doing a monthly payments but people keep telling me it isn't a good idea. i just want other people opinion on it.