How to Inspect a Used Car

The Federal Trade Commission requires dealers to post a Buyers Guide in every used vehicle offered for sale. Usually attached to a window, it must contain certain information, including whether the vehicle is being sold “as is” or with a warranty, and what percentage of repair costs (if any) the dealer is obligated to pay. The guide information overrides any contrary provisions in your sales contract. In other words, if the guide says that the vehicle is covered by a warranty, the dealer must honor that warranty. If any changes in coverage are negotiated, the guide must be altered to reflect them before the sale.

If a sale is designated “as is,” it means the dealer makes no guarantees as to the condition of the vehicle, so any problems that arise after you have made the purchase will be your responsibility. Many states do not allow as-is sales on vehicles selling for more than a certain price.

No matter who you buy from, always look over the vehicle thoroughly and take it to a mechanic for a complete inspection. Dress in old clothes that you don’t mind getting dirty and give the car a good going-over.

Do your inspection in daylight on a dry day, because floodlights can make cars look shiny and hide body defects. The car should be parked on a level surface and shouldn’t have been driven for at least an hour before your inspection.

Body condition: Check each panel and the roof, looking for scratches, dents, and rust. Watch out for misaligned panels or large gaps, which can indicate either sloppy assembly at the factory or shoddy repair. The paint color and finish should be the same on every body panel.

If you think a dent may have been patched, put a small magnet on it. The magnet won’t stick to an area with body filler. If other parts of the car have been repainted, there may be paint adhering to the rubber seals around the hood and trunk lid. 

Rust is a cause for concern, so check the body for blistered paint or visible rust. Check the wheel wells, panels beneath the doors, and door bottoms. 

Open and close each door, the hood, and the trunk. Gently lift and let go of each door, particularly the driver’s door. If it seems loose on its hinges, the car has seen hard or long use. Inspect rubber seals for tearing or rot.

Glass: Look carefully at the glass to make sure there are no cracks or large, pocked areas. A small stone chip might not be cause for alarm, though you should bring it up in negotiations. But cracks in the windshield will worsen and lead to a costly repair.

Suspension: Walk around the car to see whether it’s sitting level. Push down on each corner. If the shock absorbers are in good shape, the car should rebound just once, not bounce up and down. Grab the top of each front tire and tug it back and forth. If you feel play in it or hear a clunking sound, the wheel bearings or suspension joints may be shot.

Lights and lenses: Have a friend confirm that all lights are working. Make sure all light lenses and reflectors are intact and not cracked, fogged with moisture, or missing. 

Tires: You can tell a lot from the tires. A car with less than, say, 20,000 miles should probably still have its original tires. Be wary of a low-mileage car with new tires, and check that all four tires are the same. If there are different branded tires on the car, ask why they have been replaced.

Treadwear should be even across the width of the tread, and the same on the tires on the left and right sides of the car. Ask whether the tires have been regularly rotated. If not, the wear is usually more severe on the drive wheels. 

Aggressive drivers tend to put heavy wear on the outside shoulder of the front tires, at the edge of the sidewall. Assume the car has been driven hard if that area shows heavier wear.

Tires that have been driven while overinflated tend to wear more in the middle than on the sides. Chronically underinflated tires show more wear on the sides. Cupped tires—those worn unevenly along the tread’s circumference—may be a sign of a problem with the steering, suspension, or brakes.

Tires must have at least 1⁄16 inch of tread to be legal. Check the tread depth with a tread-depth tool—available at auto-parts stores—or a quarter. Insert the quarter into the tread groove, with Washington’s head down. If you can see the top of his head, the tire should be replaced.

Examine the sidewalls for scuffing, cracks, or bulges, and look for dents or cracks on each wheel. Be sure to check that the spare is in good shape and the proper jack and lug wrench are present.

The inside of a car may matter the most to you because that’s where you’ll spend the majority of the time while you own the car.

Odor: When you first open the car door, sniff the interior. A musty, moldy, or mildewy smell could indicate water leaks. Remove the floor mats and check for wet spots on the carpet. An acrid smell may indicate that the car was used by a smoker. Check the lighter and ashtray (if so equipped) for evidence. Some odors, such as mold and smoke, can be very hard to get rid of.

Seats: Try out all the seats, even if you probably won’t sit in the rear. Upholstery shouldn’t be ripped or badly worn, particularly in a car with low mileage. Try all the seat adjustments to make sure that they work properly and that you can find a good driving position. 

Pedals: The rubber on the brake, clutch, and gas pedals gives an indication of use. A car with low miles shouldn’t show much wear. Pedal rubber that’s worn through in spots—or brand new—indicates that the car has been driven a lot.

Instruments and controls: Turn on the ignition switch without starting the engine. You should make sure all the warning lights—including the check-engine light—illuminate for a few seconds and go off when you start the engine. Note whether the engine is hard to start when cold and if it idles smoothly. Then try out every switch, button, and lever. 

With the engine running, turn on the heater full blast to see how hot it gets, and how quickly. Switch on the air conditioning and make sure it quickly blows cold.

Sound system: Check reception on AM, FM, and satellite radio. If the car has a CD player, try loading and ejecting a disc. Take your smartphone or MP3 player with you, and plug it in and/or pair it via Bluetooth.

Roof: Check the headliner and roof trim for stains or sags to see whether water is leaking through ill-fitting doors or windows. Check to see that the sunroof or moonroof opens and closes properly and seals well when shut. Inspect a convertible top for tears by shining a flashlight up into it.

Trunk: Use your nose as well as your eyes. Sniff and look for signs of water entry. See whether the carpeting feels wet or smells musty, and check the spare-tire well for water or rust

It’s best to make these checks with the engine cool. First inspect the general condition of the engine bay. Dirt and dust are normal, but be wary if you see oil splattered about or on the pavement below. Also be on the lookout for a battery covered with corrosion, or wires and hoses hanging loose.

Hoses and belts: Squeeze the various rubber hoses running to the radiator, A/C, and other parts. The rubber should be firm and supple, not rock-hard, cracked, or mushy. Feel the drive belts to determine whether they are frayed. 

Fluids: The owner’s manual will point out where to look to check all fluid levels. Engine oil should be dark brown or black but not gritty. If the oil is honey-colored, it was just changed. If the dipstick has water droplets on it or shows gray or foamy oil, it could indicate a cracked engine block or blown head gasket, two serious problems. 

Check the automatic-transmission fluid with the engine warmed up and running. On some vehicles, the dipstick has two sets of marks for checking when the engine is either cold or warm. 

Transmission fluid should be pinkish, not brown, and smell like oil, with no “burnt” odor. The dipstick shouldn’t leave visible metal particles on the rag, another sign of a serious problem. Power-steering and brake fluids should be within the safe zone. 

Radiator: Look into the plastic reservoir that’s connected by a rubber hose to the radiator. The coolant should be greenish or orange, not a milky or rusty color. Greenish stains on the outside of the radiator are a sure sign of leaks.

Battery: Some “maintenance-free” ones have a built-in charge indicator: Green usually means the battery is in good shape, and yellow or black usually means it’s dying. These reveal the condition of just one cell and might not give an accurate reading on the health of the whole battery. If the battery has filler caps, wipe off the top with a rag, then carefully pry off or unscrew the caps to look at the liquid level. A low level may mean that the battery has been working too hard. Any competent mechanic can check out the charging system and do a load test on the battery.

Electric vehicles and hybrids: Make sure the battery is fully charged before a test drive, so you can observe its projected range. For hybrids, check the in-car display to ensure that the battery is charging and discharging while you drive.

If you can find where the vehicle is usually parked, look for marks from old puddles of gasoline, oil, coolant, or transmission fluid. Clear water that drips from under the car on a hot day is probably just water condensed from the air conditioner.

Tailpipe: Feel it for residue. If it’s black and greasy, it means burnt oil. Tailpipe smudge should be dry and dark gray. Though some rust is normal, heavy rust could mean the vehicle needs a new exhaust system. 

Underneath: If the vehicle is high enough to slide under, you may be able to do some basic checks. Spread an old blanket on the ground and look under the engine with a flashlight. If you see oil drips, oily leaks, or green or red fluid on the engine or the pavement beneath the car, it’s not a good sign. 

Examine the constant-velocity-joint boots, which are the round, black-rubber bellows at the ends of the axle shafts. If they are split and leaking grease, assume that the car has bad CV joints, another costly repair.

Structural components with kinks and large dents in the floor pan or fuel tank all indicate a past accident. Welding on the frame suggests that a section might have been replaced or cut out to perform repair work. Fresh undercoating may hide recent structural repairs.

Before you close the deal, have the car scrutinized by a repair shop that routinely does diagnostic work. A dealer should have no problem lending you the car to have it inspected as long as you leave identification. If a salesperson tells you that an independent inspection is not necessary because the dealership has already done it, insist on having your mechanic look at it. If a private seller is reluctant to let you drive the car to a shop, offer to follow the seller to the inspection shop. 

A thorough diagnosis should cost around $100 to $150, but check the price in advance. Ask the mechanic for a written report detailing the car’s condition, noting any problems found and the cost to repair them. You can then use the report when you begin to negotiate with the seller.

If you don’t know of any repair shops, you can ask for the name of a good shop at a local auto-parts store. If you can’t get referrals, look for a nationwide vehicle inspection service, such as SGS (sgs.com) or Carchex (carchex.com), or at the Car Care Council (carcare.org), an organization supported by the auto aftermarket industry. Note that there are no performance criteria for shops listed on the site.

To check for complaints about any shops, research the companies at the Better Business Bureau’s website. Members of the American Automobile Association (AAA) can use one of its recommended facilities.

If you’re going to a shop for the first time, look for certificates or window decals from AAA or the National Institute for Automotive Service Excellence (ASE). AAA-certified garages must meet certain quality standards. The ASE grants certificates to mechanics who pass exams in any of eight areas of expertise. The institute does not certify shops as a whole, but if 75 percent of the employees are ASE-certified, the shop can carry the seal.