You know you need a new car when ...

By Peter Andrew

Earlier this month I celebrated (admittedly, it was a low-key affair) my car's 19th birthday. When I bought it, nine years ago, a gear-head friend sniffily observed, "Oh, it's a BMW 520i. Bit basic and boring, but as long as you keep it topped up with oil and water, it'll go on forever."

And so it's proved. It gets routine servicing, and every few years I have to spend a couple of hundred dollars on replacing some part or other, but overall everything on it still works perfectly, and it delivers very cheap motoring. And it's now worth so little, I no longer suffer noticeable depreciation, nor have to bother with high insurance costs.

As you may have guessed by now, I'm fine with older cars. OK, if I won a huge lottery jackpot, I'd buy a whole fleet of brand new ones, but having one of the oldest vehicles in town doesn't bother me at all. However, there are plenty of circumstances when you (and even I) should know it's time to make a change. Here are five.

1. An embarrassing episode

If your teenage kids suddenly decide they want you to drop them off a couple of blocks from school, because they'd "enjoy the walk" (even though it's raining), you can be pretty sure you're seeing your car through rose-tinted spectacles. Maybe it's just not destined to become the classic you have in your mind's eye. Maybe it would look positively better as a cube of mangled metal after a scrapyard remodeling.

On the other hand, maybe the kids could use the exercise.

2. One too many stops for gas

One of the few joys of being a freelance writer is that there's no commute. Moreover, I live in the middle of a small town, so there's a supermarket, bank, deli and many bars and restaurants all within a few hundred yards' walk. So my old car sits outside the house 99 percent of the time. However, if I had a different job, or lived elsewhere, I'd almost certainly have to sell it. It guzzles gas like it's 1995 -- which it was when it was made.

In the week it was first registered, the average cost of gas across the country was $1.08 a gallon. In the same week in 2014, it was $3.33, according to the U.S. Energy Information Administration. Old cars rarely do fuel economy in the way modern ones do, and you may well find that, if you have a high annual mileage, you could cover a big part of your new lease or auto loan payments out of your monthly savings on gas.

3. An environmental epiphany

Replace your 19-year-old BMW 520i or your 10-year-old Ford Focus with a newer car, and your personal carbon footprint is almost certain to fall. But will that save even a single polar bear? To start with, your old car -- unless you scrap it -- is still going to be on the road, and is likely to be belching out precisely the same number of Earth-harming carbon atoms as it was when you were driving it -- maybe more, if the new owner doesn't bother to service it properly.

Meanwhile, the damage done to the environment when a new car is manufactured is far from negligible. A 2010 report in The Guardian put the carbon-dioxide equivalent (CO2e, in green jargon) of producing one of the tiniest European super-compacts at six metric tons, while the same number for a Land Rover Discovery was 35 tons. You may have to scale that up for the biggest domestic SUVs.

There are also huge costs to the environment in water and landfill usage whenever a new car is built. None of this is intended to stop you caring about the planet, but it means that owning an apparently carbon-unfriendly old car isn't always a bad thing. If you're the sort who worries about your green credentials, buying a brand-new gas guzzler is generally harder to justify.

Still, if your car routinely leaves a plume of smoke in its wake and you suspect its next home will be a junkyard instead of a garage, there may be some environmental sense in seeking a newer, greener model.

4. A series of breakdowns

I had an overindulgent lunch today, and our designated driver Mike has a 1997 Volvo. So I asked him en route to the restaurant about the pros and cons of having an older vehicle. He said his biggest issue was reliability. Too often, he said, he leaves his house to drive somewhere, and his car just won't start. But he plans to stick with his 20th century vehicle, because it's so cheap to run.

That wouldn't do for me, and I suspect it wouldn't for you either. Things may be different for Mike, who's retired and embodies Zen calm, but when you and I get into our vehicles, we expect to get to where we need to be. So unreliability may be an issue that forces you to change cars.

5. A costly repair

Mike's car seems to need repairs every other week, and mine seems to need them every other year. But, every time I take mine for a service, I ask the mechanic whether he or she reckons it remains a good car to have. I know I can't ask for a guarantee, but I want a professional opinion on the chances of it remaining a good runner for the following year or two.

So far, I've been lucky, and have been told it's still a good bet. One day, I know, that bet will turn bad. Perhaps it will be during a routine service, or perhaps, hood-up, on the side of some road, but it's pretty much inevitable I'll eventually be told I'm going to have to spend thousands to repair something that has a market value in the hundreds. Then I'll have to decide whether to invest many thousands on a new, equivalent replacement, or just a few thousand on another geriatric vehicle that I hope will give me a similarly cheap driving experience. What would you do?

P.S. When I went out to take the picture (above) this morning, I moved the car. But, when I went to get out, the interior driver’s door handle wouldn’t work, and I had to lower the window and use the exterior one. Dammit! I knew I was tempting fate when I wrote this article.