What should be checked on a used car before or after buying?
Have an independent mechanic inspect it, ideally before you buy or early in any return window. The essentials are brakes, tire tread and age, suspension and steering, leaks, fluid condition, belts and hoses, battery and charging, a scan for stored and pending codes, and a test drive. Ask for a prioritized list, so you know what needs doing now and can factor it into your decision.

The checklist
Underneath and at the wheels - Brake pads and rotors measured - Tire tread depth, age (DOT date) and wear pattern - Ball joints, tie rods, bushings, shocks and struts - CV boots and axles - Oil, coolant, transmission and differential leaks - Exhaust condition and catalytic converter present
Under the hood - Oil level and condition - Coolant level and condition - Transmission fluid condition where checkable - Belts and hoses - Battery test and alternator output - Signs of accident repair or rodent damage
With a scan tool - Stored and pending codes - Readiness monitor status (recent code clearing) - Hybrid system and ABS codes where relevant
On the road - Cold start - Shifting, braking, steering, noises and vibrations
Ask about maintenance history
Records showing oil changes and major services, especially a timing belt on engines that have one, are worth a lot. Missing records aren't a deal breaker, but they change what you should plan to do first.
What we provide
Photos of anything notable and a prioritized list: needs attention now, soon, and later. One customer's daughter bought a car from an online dealer with a seven-day return window; we inspected it inside that window and took care of a few minor items right away.
From drivers who came to us
My daughter just bought her 1st car, an 2014 Acura-Hybrid, from SHIFT who has a 7-day full-refund return policy. Dylan & Derrick thoroughly inspected the car, and made some minor adjustments/repairs in short-order.
I brought in my recently purchased, used 2013 highlander for a transmission service and rear differential fluid change… even let me know that my differential fluid was actually looking pretty new and wouldn't need servicing.
They were able to send me a prioritized list of items that would need attention… and which items could be done together… gave me their honest professional opinion on how long I had before needing to address the above items (my car is almost 20 years old and over 190,000 miles!), rather than pushing me to do the work immediately.
Excerpts from verified customer reviews on Yelp.
More questions
When is the best time for a used car inspection?
Before you buy. If you've already bought from a dealer with a return window, book early in the window so there's time to act on the results.
Does a recently cleared check engine light matter?
It can. If codes were cleared recently, the car's readiness monitors won't be complete. A scan shows that, and it's a reason to ask questions.
Who is responsible for the smog certificate in California?
In most private-party sales, the seller must provide a valid smog certificate. Check the DMV's rules for your situation.