Here, do all this stuff. It should get you started in the right direction.
-Questions to ask a private seller over the phone:
(A used car dealer would not know the answers to most of these questions, you’re on your own there. If you are buying an out of warranty car from a dealer -don't- take their word for anything mechanical on the car. It's the buyer's responsibility to make sure they know what they are buying, not the dealer's.)
Get VIN number and run an Autocheck or Carfax.
Check the VIN for theft or salvage here:
click
How many miles are on the car?
How many miles were on the car when you bought it?
How long have you owned the car?
Why are you selling?
Where did you buy it?
What maintenance records do you have?
What recent work has been done to the car?
What work does the car need as it sits?
Has the car been in any minor or major accidents?
When was the last time the oil was changed?
How often is the oil changed?
How often does the oil need to be topped up?
Has it ever been run low on oil?
Casually ask them how long the tires last. That can give you an indication of how it has been driven.
Has the car ever been raced?
Has it ever been overreved due to a mis-shift? This can lead to cracked retainers on AP1s.
Where was the car stored? A garage is ideal.
-Things to check before leaving for a test drive:
Bring something to take notes on and write down any pluses or minuses for each car you look at. After you see a few it can be hard to keep them straight without notes.
Ask the owner to not start the car before you arrive to see it. Some problems will only be evident when the car is cold. If you know how to not burn yourself, hold your hand next to the engine or header to verify the engine is cold when you arrive.
Try to get a look at their garage. The condition of their garage can (but not always) indicate how well the owner takes care of their car.
Check for any leaks where the car is parked. Keep in mind there could be funk on the ground unrelated to the car. I prefer to see where the car is normally stored.
Check the oil for level and color. Dark oil is not ideal but can mean it just needs to be changed. Oil below the low mark is very bad. Oil that is cloudy or milkshake colored can indicate a blown head gasket or cracked head and that you should pass on that car.
Check the coolant for level and color (Don’t open the radiator cap on a hot engine!) Coolant that is low is not ideal, but may not be a big deal. Coolant that looks like a milkshake can indicate a blown head gasket and that you should pass on that car.
Look under the oil cap and into the valve cover. Ideally it should look like the oil on the dipstick. Sludge or a milky color can indicate lack of maintenance.
Check the brake and clutch fluid color and level. These can get dirty fast so dark isn’t always a problem. If they are low that could indicate brake or clutch trouble and bills in the $100-300 range at an independent mechanic. Much less if you can DIY.
Look at the battery terminals. If they are corroded that indicates lack of maintenance by the owner. A battery is cheap and easy to replace, but this sort of thing can help you determine if the car has been well cared for or not.
-During the initial test drive:
Drive on the highway and around town like you normally would. Shift up and down through each gear. Take the car to redline without abusing it or breaking the law. Try braking from different speeds. Let car decelerate in gear from several gears at different speeds. Pull into a parking space. Use reverse. Try to make it show you any faults.
Does the car start and idle normally when cold?
Does the car start and idle normally when hot?
Is there obvious blue smoke or –lots- of white smoke coming from the tailpipe? Both are probably deal breakers. A small amount of white smoke is normal.
Find an empty road, get up to about 30 in third gear and floor the accelerator. If you can see the engine RPMs climb independent of the car accelerating, the clutch likely needs to be replaced.
On the same empty road, brake from highway speeds with a light grip on the wheel. Does the car pull to one side? If it’s not caused by the crown of the road that could be things like tire pressures, alignment or bad brake calipers.
Is the steering wheel straight when you’re going straight down the road? This is a pet peeve of mine and can be caused by a variety of problems, some inexpensive, some expensive.
Does the cruise work?
Does the emergency brake work?
Find an empty parking lot and do slow figure eights both forward and reverse. Listen for any strange noises. In a FWD car you can check CV joints this way
-Now park the car and inspect the following:
Now that the car is warm, is the engine making any unusual sounds?
Pull the air filter out, is it clean or dirty?
Is the wear on the steering wheel, pedals, shifter, carpet, seats, etc consistent with the miles on the odometer? This is a good way to confirm that the odometer hasn't been tampered with and can give you an idea of how the owner takes care of the car.
Do all the keys work all the locks and start the car?
Do all the seat controls and compartment doors work smoothly?
Look under the dashboard on both sides for non-stock wiring that could indicate modifications. This may or may not be a big deal, but it’s worth being aware of and asking the owner about.
Is there water in trunk or under the trunk tools? Put your hand on the interior carpet near the footwells. Is there any evidence of wetness or water intrusion?
-Now take a look under the car
Are there any signs of leaking from the engine, transmission or differential?
Any signs of rust in the wheel wells or underbody? If possible, check behind the rubber strip at the rear wheel arches.
Any damage from bottoming out, accidents, improper jacking, etc?
Torn axle boot, tie rod boots, or ball joints. If a boot is not dry that part probably needs replacing
Exhaust leaks or damage. Leaks can usually be identified by black soot where two exhaust parts join.
Look at the brake rotors. If they are scored with deep grooves the brakes likely need replacing. If you are confident the brakes are cool, you can run your finger over the edge of the rotor to feel how worn they are.
Run your hand along each tire’s tread at both the inside and outside of the tire. Tires can look fine on the outside tread and be worn bald on the inside. Worn more or less in the middle usually means incorrect tire pressure. If the tread feels “choppy” and not smooth there is likely an alignment or suspension problem. This could be anywhere from a $100-1000+ repair, not including the cost of tires.
With the steering wheel unlocked, grab each wheel or tire at 9 o’clock and 3 o’clock and shake or push-pull it as hard as you can in and out. If you feel clunks that can point to things like bad tire rod ends or wheel bearings. Do the same at 12 and 6. If there are clunks or strange noises, expect a $100-300 bill at each corner, more if it's wheel bearings.
-Check for signs of body work or accidents
Verify that all the VIN stickers are in place and match the car’s VIN.
Open the hood and look at the bolts holding on the front fenders. Often there will be paint worn off of these if the fenders were removed.
Same with the door and trunk hinges.
Look at the radiator support. Does the paint look strange or is there evidence of replaced parts? Poor repair work from a front end collision can be visible there.
Look for overspray onto any black panels near a painted body panel. Fender liners and door/windshield trims are good places to look for overspray.
Check door and panel edges for paint lines.
Check the sides of doors or door jambs for bodyshop stickers.
Check that body panel gaps are even. This includes the bumpers.
Look at adjacent panels from different angles and in different light. Poor paint work can show up as inconsistent color or texture between panels.