Much of the test drive should happen before you actually drive. It's tempting to hop in the car and take it for a spin, but it's wise to inspect the car carefully before — and after — the drive to determine its condition and attempt to confirm the answers the seller gave you before you arrived for the test drive.

Remember that a used car's current condition and the way it was cared for are at least as important as the style, features and fit when it was new. When you're done with this test drive, you may not know for sure if the car is mechanically sound without the help of a mechanic, but you may know if it's definitely not — and be able to rule it out without paying a professional up to $100 to tell you so. You're also looking for smaller problems that may help you reduce the price.

Wear clothing you don't mind getting dirty, bring a flashlight, a flat refrigerator magnet and always — always — evaluate cars in daylight.

Rust Can't Hide

Despite advances in manufacturing, rust remains one of a vehicle's greatest enemies — one you should be able to detect on your own. Rust is generally more damaging to a car's appearance and value than to its ability to get you where you need to go. It's expensive to repair well and nearly impossible to reverse.

Start at the Bottom

Start by looking at the car's undercarriage (underside). Use your flashlight to inspect the floor pans (the metal that forms the floors) and frame rails (the structural members that run around the perimeter of the car's underbelly). Look for rust. Also look for marked differences in the condition of different sections. One pristine or freshly painted section in an otherwise moderately rusty car is a reliable indication that part of the vehicle was repaired. Did the seller disclose any accidents in the car's history?

While you're down there, look up into the wheel wells for rust. Take note if the car seems to be dripping anything (check out the driveway and/or the garage floor if you can) and look for rust and signs of wear on the muffler and exhaust pipes.

The Tires

Don't get up yet. The tires tell a lot about a car and how it's been driven and cared for. You're looking for several signs:

Overall wear: Do the tires have enough tread on them to be safe, or are they bald or close enough to it that you'll have to replace them soon? Look for tread-wear indicators, which become visible when the tread has worn down far enough that the tires need to be replaced. The indicators are ridges that run across the surface of the tires, perpendicular to the sidewall. Each tire has six of these indicators evenly spaced around its circumference. The location of each is marked by an arrowhead found on the sidewall, typically at the base of the tread.

If you're not sure about the wear indicators, try the penny test: Hold a penny, head side toward you, and insert the top of Lincoln's head into the tire tread until the coin's edge rests in the groove. If you can see the top of Honest Abe's noggin from the side of the tire, the tread is probably worn too far. If the top of Lincoln's head disappears into the groove, your tire has some life left. It's simple: If you see Abe's head, there's not enough tread. Repeat with all the tires.

Uneven wear: Have all the tires worn evenly from one sidewall to the other? Try the penny test to verify a difference. Tires should wear evenly. If they don't, it's likely the car has been in an accident and/or is out of alignment.

This does not compute: Does the car have low mileage but worn-out tires? Why the contrast? Maybe the odometer is not accurate. It's not a crime to put used tires on a car, but you should try and find out what's behind the disparity. The same is true if the car has low mileage yet brand-new tires. Perhaps the owner decided to upgrade, had a blowout or simply replaced all four tires. It can't hurt to ask about anything that just doesn't make sense.

The Walkaround

Stroll around the car looking for rust, dents and dings. Check how well the hood, doors and trunk/hatch lid meet the body. All should close and seal well and rest on the same plane. Try all the doors and their windows and locks. (With a convertible, try the doors and windows with the roof up and down.) Some of these tests may seem unnecessary, but every little problem could become your problem, and every shortcoming can be used to drive the price down.

Whip out that refrigerator magnet (the flexible kind that looks like a business card is best). Place it on at least one point of every major panel of the car's exterior. It should stick. If it doesn't, it means one of three things:

·        The panel has been repaired with Bondo, fiberglass or some other nonmetallic dent filler.

·        The car is made of fiberglass, as is the Chevrolet Corvette.

·        That particular panel is nonmetallic or nonmagnetic (aluminum). In the case of 2 and 3, chances are that the whole car, or like panels, will also not support the magnet. Whole panels — let alone whole cars — are seldom rebuilt with body filler, so you'll know you're onto something if the magnet doesn't stick to part of a panel, or one of four doors. Be aware that bumpers and grilles tend to be molded from plastic nowadays. WARNING: Be sure only to use a pliable magnet, or place a piece of paper or cloth between a metal or ceramic magnet and the car; you don't want to scratch the paint.

The Trunk or Hatch

Check out the trunk (or "hatch," if the car is a hatchback, sport utility vehicle or minivan). If possible, lift the carpet and check for rust. Will the cargo capacity meet your needs? Is the spare tire in its proper location, full of air and in good condition? Pay attention to how simple or difficult it is to lift the trunk or hatch lid. Does it stay up or fall on your head? Will you be likely to hit your head on it even if it stays up?

The Engine Compartment

You don't have to be a mechanic to learn something about a car and its owner by inspecting the engine compartment. Pop the hood and perform these checks:

·        Take a good look at the overall condition. Is the engine clean, or are there signs of leaking oil or other fluids? Take a mental picture, because you'll want to look again after you drive it.

·        Check for rust, particularly on the shock or strut towers, the points at the corners near the windshield to which the front suspension is anchored.

·        Do you see any sign of fresh paint (or paint that is clearly newer than elsewhere on the car)? Have any of the rubber bumpers been painted over? These can be signs of an accident or simply a re-paint job.

·        With the engine turned off, check the underside of the fan belts (the surface that comes in contact with the pulleys) for cracks and obvious wear.

·        Pull the oil dipstick, wipe it clean with a rag, and reinsert and remove it. Is the level correct? Is the oil dark and dirty? Both are signs that the car isn't getting the care it deserves. You can also look for beads of water on the oil clinging to the dipstick, which could reflect a costly head gasket problem.

·        If the engine hasn't run for hours and the radiator is cool to the touch, remove the radiator cap carefully and slowly using a rag (the car's coolant system is pressurized and can spray, causing injury; open it only if you know it's cool). Is there a layer of oily film floating on the top? Is the coolant clean and green or rust-colored? A layer of film is caused by oil, which reflects a costly head gasket problem. A rusty color is caused by, you guessed it, rust, which reflects that the vehicle has been neglected.

Start It

Go ahead and start the car. Does it start easily? Run smoothly? Don't hesitate to test all the lights and signals, inside the car and outside. Same thing for the wipers, heat and air conditioning, and cigarette lighter.