As cars age, they require more repairs. As the repair bills mount we naturally begin to wonder if we are throwing good money after bad. Should we continue with the old car, or get another newer one? It's a problem faced by nearly everyone sometime or other. Some people buy a new car every year or so, just to avoid repair problems. When you consider the depreciation on new cars, this would be the most expensive solution. Some people keep a car until it needs to be junked. They will have paid the least for their transportation miles, but would have had the most breakdowns. So it would appear that there is a trade-off involved. Pay extra for fewer breakdowns, or pay less and put up with the breakdowns.
It comes down to this; what can you afford to pay to avoid breakdowns? In other words, is your time spent waiting for repairs more important than the repair costs? For instance, if you are handicapped and really stranded without your car, or you use your car constantly to make a living, or you have plenty of money and the cost is nothing to you and you can not afford the time to get it fixed, then you need to stay with new cars. If, however, you are retired and only use the car occasionally, or have friends with cars, or you have a second car, or you are really strapped for money, then perhaps you should keep the old one, and repair it when necessary. You can afford to lose a little time to get it fixed.
There can come a time, however, when it may not be worth the money to keep repairing a car. An example is an extreme case of rust. Sometimes the floor rusts through, springs are ready to break, and the frame rusts until it sags. This would take major bucks to repair, resulting in more money invested than the car was worth. Time to give up. However if the car were repairable for less money than it would cost to replace it, the better option would be to fix it. For instance, if your car was worth $5,000, and needed $1,000 to repair it, your choice is to either do that, or sell it and buy another one for $6,000. Would the $6,000 car be better for you, or would you be buying someone else's problems? You might be better off with the one you have. "Better the devil you know", as the saying goes. At least you have a pretty good idea about future repairs on the one you have. The one you're buying is a crapshoot.
A final consideration is simpler. Do you like the car? Do you like driving it and looking at it?
I once had a peeling pea green Plymouth Neon. It ran like a top; got great mileage. I hated it. If it had been my only transportation to the grocery store, I would have starved to death. If you like it, and it's not terminal, keep it. If you don't like it, dump it. Life is too short to be driving ugly cars.