People on tight budgets are often tempted to skip some routine car maintenance services, or at least to delay an appointment with the auto shop.

However, poorly maintained vehicles cause thousands of wrecks each year. The bill for accidents resulting from unperformed vehicle maintenance tops $2 billion a year, according to a 2004 study by Car Care Council, an advocacy group based in Bethesda, Md.

Even if you are lucky enough to avoid a crash, putting off maintenance is likely to reduce your car's life span.

"If you don't maintain your car, you're taking a vehicle that might have been driven for 200,000 miles over its life, and you're knocking it down to maybe 150,000 miles," says Philip Reed, senior consumer advice editor at Edmunds.com.

The true cost of not maintaining your vehicle can include hefty repair bills for bad brakes, failed emissions tests and maybe even a failed engine. Following is a list of some common maintenance requirements for automobiles and the costly problems that can occur if they aren't completed.

1. Consistent oil changes 

Regular oil changes help keep your engine clean and lubricated, says Deanna Sclar, author of "Auto Repair for Dummies."

"Oil cuts down on the friction that can literally wear away the parts of the engine," she says. "One of the most important maintenance-related things you can do is change your oil frequently."

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