Ideally you'd get ab obd2 reader and check for any pending or historical codes. Also check under the car for rust levels. Sniff test for any mold smells, look for any signs of water inside. Check tires, do the shock absorption tests. Listen when revving the engine for any "odd noises" or bogging down sort of noises.

Best thing is if all that looks good, ask to take it to a local mechanic and pay them to do an thorough check of the car - what's worn, what's broken, will it pass any state checks etc. Expect to pay for an hour of labor.

If they balk I'd be really leery of buying - Wonder what they want to hide.

If you don't know anything about cars its probably worth the money for a pre purchase inspection by an independent mechanic

look underneath. if the car is from an area that salts the roads, there will be a lot of rust. don't buy it. you can't fix rust like that. and don't buy a hyundai.

Rust, weird noises, etc. If you get there and the engine is warmed up it's a good chance that they're hiding some issue with it running/starting. Also if the engine has been cleaned.

Also things like service history, mileage, and other general wear and tear. Ask questions about issues the car has had, if anything was replaced etc.

• Check the dipstick. Black oil isn't necessarily bad, but clear oil at least means that it's maintained to some degree. And check the level, of course.

• Check the battery poles. Ideally there shouldn't be any rust on them. If the poles are greasy, the owner knows how to ensure they last for a long time.

• While under the hood, Check for any rubber hoses that seem like they're crumbling

• Yank one of the front wheels sideways. There should be no wiggle. If there is, you might need to replace the "steering knobs" (I have no idea what the English word for it is). None is good, a little might be OK. Loads is a problem.

• Some rust on the brake disks isn't necessarily an issue. Generally, they're the parts that rust the most, and some spots generally just means that that the car has been stationary for a while. Some heavy braking will wear away these spots.

• Run your finger over the brake disks. If there is no lip around the edge, they're pretty new or at least not used. Some lip is expected as the pads have worn into the disks for a while. A very big lip probably means that the brakes should be replaced (Doesn't cost much, and it's pretty easy to do yourself)

Along with what others said, look under at the wheels where the transmission or differential connect to the wheel. There is a rubber boot, make sure they're not cracked or leaking grease.

Check around the vehicle at the seams of where the body panels and doors meet, the headlights. You're looking for anything that looks like the segments aren't spaced the same. Mainly you're checking for previous damage that may have been repaired. If you see stuff not spaced evenly it could mean it was in a collision at one point. Might not be a problem but could mean damage like the frame is bent which can cause problems.

Smell the inside carpets, maybe if you can make them slightly moist, see if it smells musty or look for rust under the seats where the metal is. Could be flood damage. This can lead to weird electrical problems for example and other problems like odors in humidity.

Pull the carpet up in the trunk, check if it has the jack and spare tire, and check if any water accumulating in there.

EDIT: Also check the ceiling inside along the top, look for stains that could indicate a leaking roof.

Depending on how much the car costs, pay for an independent pre-purchase inspection. Few hundred bucks but worth it. I bought a car from Florida a few years back and had it shipped to Seattle without seeing it in person first, but getting an inspection done on it before I pulled the trigger gave me all I needed to know (and I wouldn't know exactly what to look for anyways)

Corrosion.

How rusty is the under side? Splotches can mean nothing... Flaking is bad or otw to it.

Is there corrosion or water damage in the cabin or under the hood? Run. Pull the inside fuse box cover off or look behind the glove box.

Beyond that... Definitely drive it. Listen to it cold start... Once up to temp drive it (safely) hard.

Pop the hood, trunk, open all the things... Anything look or smell weird?

Carfax/report can shed some light but isn't perfect. Came from Florida right after a bad hurricane... Pass. No oil changes until 30-40k and llc.owned? Prob rental... Possibly abused. Sporadic oil changes? Toss up... Doing your own work obviously won't generate a point... Some shops don't bother... Etc.

Take it to your mechanic or hire a mobile mechanic to inspect it. It's worthwhile even on the cheapest used cars available nowadays. I and several of my friends have used Lemon Squad before with good results if the car isn't local, but there are plenty of similar services online. If it's local and you know/trust a mechanic already take it there.

When you arrive, make sure the engine is cold. Check all the fluids. If there's milkshake in the radiator or the dipstick, that's a no-go. if the trani fluid is dark and smells burnt, that's a no-go. Start it. If it's hard starting, maybe pass. check the paperwork, make sure the VIN matches and that the title is clear. I've never had an issue with a car that had a reconstructed title, but also I've only bought cars older than 2000, because fuck modern cars

First, know the brand/model you're shopping for so you can read about known issues.

For example, in some Toyota and Honda engine/transmission combinations there are known transmission cooler failures that had recalls or known failure modes. Verifying that had been addressed is important.

Otherwise I just don't buy anything other than Honda or Toyota, and maybe Mazda. The difference in reliability and ease of maintenance from those 3 to all the rest is dramatic. And if you drive one, you'll know immediately if it's alright.

It's worth spending more at purchase for these to minimize down time due to maintenance. Our Hondas just go, every time. We have some from the early 90's in my family - they ain't pretty, but they just work.

Brakes-male sure their not making noise and the rotors are not all scratched up

No noise from the suspension going over bumps

Then for a particular model of car, research the common problems. Like if the water pump is known to go bad at ~100,00 miles and the car has 95k on it, try to see if it has been replaced recently

Most things aren't deal breakers and you can just fix them after you buy it, but that cost of repairs should be taken off the buying price imo

There isn't much you can do/look for these days. Was it well maintained is the real question, and that cannot be figured out except by tearing the engine apart and measuring cylinder wear (using tools few mechanics have). You are looking for signs of trouble, but most of what you care about is hidden, while cosmetic things that don't really matter are visible.

I have a list but it's easy too long to post here. I tell the sales guy to go away since it's going to be about half an hour before I am even ready to start the car.

I guess one simple piece of advice is to get a code reader and plug it into the OBDII port to see if there are any codes. Done will verify the mileage.