Savvy consumers, however, know what to look for in a used vehicle by asking the right questions. The experts at BMW, one of the first automakers to initiate a manufacturer-backed certification program, suggest starting with the following:

1. What are the dealers' criteria for selecting and certifying a vehicle?

CPO vehicles should be late model years, have low mileage and be in excellent condition with no history of major damage. They should also pass a comprehensive inspection process of electrical, mechanical and cosmetic items and all necessary repairs and scheduled maintenance should be completed.

2. What is covered under the warranty?

Once a vehicle is certified, it should be covered by a warranty that extends beyond the original factory warranty. It should typically include some of the same features as a new-vehicle warranty: everything except those items related to upkeep, normal wear and tear, the body and interior and accessories.

3. How long is the warranty period?

The length and terms of CPO warranties vary greatly among manufacturers. The CPO BMW Limited Warranty, for example, adds an additional two years or 50,000 miles to a new car warranty of four years or 50,000 miles for a total of six years and 100,000 miles.

4. Is the warranty transferable?

Be certain the warranty can be transferred to a new owner if the vehicle is resold. Only with a transferable warranty can it still retain coverage.

5. Who provides service if it is required?

Make sure that service work covered under the CPO warranty will be performed at any of the manufacturer's retail outlets, by trained technicians using genuine parts. The CPO warranty should also cover roadside assistance (e.g., flat tire repair, lock-out service).

For more information, visit http://www.bmwusa.com/CPO/.

When buying a used car, knowing what to look for can help you drive a real bargain.