The year 2008 is turning out to be the worst year in a decade for new car sales. Because of the economy, people are keeping their cars longer.

But just how long should you expect your car to last?

Here's a check list of things you can do to extend the life of your car, and improve your gas mileage while you're at it.

The average new car on the road is traded in after only 4 years and 55,000 miles. But transportation experts say most passenger cars could run for 150,000 miles or more.

Walter White of Seattle found the secret. His 1990 Toyota Corolla has nearly 170 thousand miles. Walter says it still gets up to 30 miles to the gallon.

Walter's wife Connie drives an '89 Mazda minivan with nearly 198,000 miles.

The secret is not really a secret at all. It's just something many drivers don't like to bother with.

"The key is the proper maintenance," explains Dave Armstrong, fleet manager at AAA Washington.

Something as simple as clean oil at the right level adds years to the life of your engine.

"If you have a component that's starting to fail, it's going to put stress on a related component." Armstrong adds.

Dirty or low oil can tear up your engine. Dirty corrosive anti-freeze can damage your radiator.
If your alternator's going bad it can wear out your battery.

Translation: ignoring maintenance is a formula for breakdowns, lousy fuel efficiency and eventually, very expensive repair bills.

As they say in the automotive service industry, pay now or you'll pay a lot more later.

When's the last time you got an alignment? Armstrong says poor alignment can strain your suspension system and wear out your tires.Speaking of tires, regular rotation means even tread wear and longer tire life.

"Every time you put gas in your car you should always walk around the car and check your air pressure. That alone will save you a lot of money," said Armstrong.

Proper air pressure helps your tires last longer and improves your gas mileage.

So let's review:

Tire pressure and rotation

Proper alignment

Good oil and other fluids

Regular engine inspectionsFollow your manufacturer's recommended intervals.

"I knew if I took care of it, I would have it for a long, long, time," says Connie Bigelow. And that's what's happening.

There's no secret; just routine maintenance.

Armstrong says it's not unreasonable to expect 150,000 to 200,000 miles out of a car today.

Walter and Connie are not only keeping their cars running, they're saving as much as $6,000 to $7,000a year.

More information:

Wikihow: How to extend the life of your car

Get rich slowly: How to extend the life of your car