Should he fix his car up or just wait to buy a new one?

My best friend currently has a 95 cavalier sedan which his parents handed down to him when they got new cars. He is interested in buying a new car but has no credit so of course he would need a co signer. He is interested in purchasing a 09 NIssan Altima Sedan. His other option is to fix his current car up (i.e., spray it over, tint over the windows, put in a new radio, and of course work on the engine) The car runs, the a/c & radio works, its just that of course @ times there are some major work that has to be put into the car to make sure it stays that way. I think he should just wait until summer or something & get the new car he has his eye on rather than put even MORE money into the old car that should just get sold to a chop shop. What do you guys think, should he spend even more money on the Cavalier or should he just start fresh and get a new car??