Should I buy a car, or just share one for free?

I could drive a '97 camry le but I would have to share it with my brother year round, and my sister during the summer. We are a 5 person family with 3 cars and a moped. I work 2 jobs so I have $5k saved up for a car alone and I am 16. I'd like to buy like a 2000 or 2001 celica, eclipse, prelude, etc. I know the prices and I can afford them. So should I buy a car or just share one?