If you've ever asked yourself, "Should I repair or replace my car?" the answer is usually pretty straightforward. Hanging on to your older car for as long as you can makes solid economic sense. As long as your ride isn't costing more than your car is worth and is relatively reliable, you're in good shape. Your insurance will typically be lower on an older vehicle, and you can use the money you're saving for a down payment when the time does come to make a change.
There are a few extenuating circumstances that should influence your decision. One consideration is how well the car has been maintained over time. A well-maintained vehicle will perform better than one that's been abused and neglected. If the car was a low-end model to begin with, that will have an impact on its useful life, too. When you're trying to eke 20,000 more miles out of a car that's been hemorrhaging oil all over your garage, you have to ask yourself if this is just the last in a long line of calamities. If it looks like a major failure is looming, it might be a good idea to consider making a change sooner rather than later.
If you can perform some of the repairs yourself, keeping your car a while longer is probably still a good idea, even if you have to add a yearly membership for roadside assistance to your list of expenses. If you aren't handy with cars, or you live in an area where a breakdown could put you in harm's way, then that becomes a big incentive to upgrade. Another would be if you rely on your car for your livelihood. When you're in sales and you're cold-calling all over the county, not having a reliable vehicle is more than an inconvenience.
An automobile can represent more than a means of transportation to many people, too. Cars might symbolize status, freedom and other non-transportation related ideals. When those motives become part of the mix, deciding when to sell can get more complicated. If you don't have a car payment now and you can't afford one, you'll just have to weigh the intangible benefits of a nice ride against the real and immediate need to eat regularly.
If you decide to take the plunge and get rid of your car in favor of something newer, do your homework. Trading in your vehicle is the most convenient way to upgrade, but it might cost you. Dealerships typically pay wholesale prices for trade-ins, and you'll be able to get more for your old car if you sell it yourself instead. Remember, it may be an eyesore and a big disappointment to you, but to someone else, it could be a diamond in the rough.