DO -- Shop options. As vehicles age, the options price gap narrows. Loaded used cars cost more, but deliver desirable options for much less than original cost. Well-optioned, deluxe models are easier to resell than base models of the same vehicle.

DO -- Get everything in writing: Especially price, terms, repairs, and/or trade-ins. This should be written into the sales agreement.

DO -- Know the difference between age and depreciation: With late-model used vehicles, the previous owner has absorbed a big chunk of the vehicle's total depreciation. Try to buy before the depreciation curve levels off and while the car is as new as possible. This generally falls in the two-to-four year old range, although it varies by make and model. Study prices versus vehicle age to determine that ideal window.

DO -- Investigate the lease and rental market: There are many excellent lease return cars on the market, especially cars driven by an individual for personal use, or in a company. Motor pool cars (e.g. utility company vehicles), less so. Maintenance schedules are excellent on rental cars, but drivers do abuse them.

DO -- Protect your investment: The remainder of the original manufacturer's warranty can usually be transferred. Seriously consider purchasing an extended warranty (3 months,/3,000 miles) free, and low-cost protection beyond that. When shopping any warranty, check the fine print, watching for excessive deductibles. And be sure the automaker recognizes the warranty - if not, you may as well use your warranty as a floor mat.