Buying a used car is one of the purchases where a bit of hands-on checking can save you thousands — most serious problems leave visible clues if you know where to look.
Where to actually look
Tires — check tread depth and whether wear is even across each tire. Wear that's heavier on one edge can point to alignment or suspension issues, not just an old tire.
Undercarriage — look underneath for rust, especially around the frame and exhaust, and check for fluid leaks (a few drops under the engine or transmission area after it's been parked are a real warning sign).
Engine bay — look for corroded battery terminals, cracked belts or hoses, and check the oil on the dipstick — dark, gritty, or low oil can point to deferred maintenance.
Panel gaps — the spacing between body panels (around doors, the hood, the trunk) should be even all the way around. Noticeably uneven gaps, or paint that doesn't quite match between panels, often means the car has had bodywork after an accident.
Odometer and interior wear — worn pedal rubber, a sagging driver's seat, or a steering wheel that's noticeably more worn than the mileage would suggest can be a sign the odometer reading doesn't tell the whole story.
The check a walk-around can't do
Get the Vehicle Identification Number (VIN) and run a vehicle history report before you commit. It can surface things invisible to a physical inspection: whether the car's been in a reported accident, had a salvage or flood title, or shows an odometer reading that doesn't match earlier records. This is genuinely one of the highest-value checks for the time it takes, and it's worth doing even for a car that looks perfect in person.
The one thing people forget
Have a mechanic you trust — not the seller's mechanic — do a pre-purchase inspection before you finalize anything. It typically costs far less than the cost of a problem it might catch, and a seller who refuses to allow one is itself a red flag worth taking seriously.