First, how do you survive on $100 a week? What do you do? When I was 17 i was making over $300 a week while going to school full time.
Keep the Maxima, take the money you’d put into a car, and save it. That way, when you get the car you REALLY want down the road, when you make better money, you’ll have some money saved up to do things you feel necessary. Also, the best advice I can give, is save for the parts you REALLY want, and do it right the first time, so you’re not just wasting money replacing things you already put in/on it that weren’t exactly what you would like.