> All i know is lower mileage is better?
Not so fast... On slightly used car low mileage = better car. But after some miles (say about 50K miles), MUCH more is dependent on the maintenance of the car. For example, I have a 94 Civic with 188K miles. Yet the engine + tranny + suspension runs like a new car! But I've seen plenty of other cars that are falling apart at just 60K, 70K, etc. miles.
So see the list below about what to do.
I'm going to assume you are talking about low priced used car.
Here's some rules you should consider when buying a used car
(1) don't get sold on the paint job = meaning cars having good exterior, fancy CD radio, etc.
(2) look for car with sound ENGINE + TRANNY + SUSPENSION.
(3) test every button, knob, switch, slider, etc.. Ex: even in the summer test out the heater & even in the winter test out the AC (if you can). Slide the AC/heater to fan1, fan2, fan3, etc. then slid the vent to defrost, front, bottom, etc. Test the high beam, low beam, etc. Test (flip) the visor. Test the alarm. Test all 4 doors. Test the rear defogger.
***** TEST EVERYTHING.
(4) BEFORE the first start, open the engine bay and see if the engine is already warmed up. Many engines starts well when already warmed up, but may have problems when cold (or cold start).
(5) test drive with the sound system off and window down. Listen for weird sound coming from the wheels & suspension.
(6) Look inside the engine bay to see if you can see see leaks, etc. It is normal to see some oil and grease. But too much means that the car is leaking oil somewhere. Too clean (really clean) means they just wash the engine bay - possibly hiding some oil leaks.
(7) check the engine oil dip stick. If the oil is BRAND NEW CLEAN, the seller MIGHT be hiding something. If the oil is jet black and /or smells like gasoline (or burnt), you might have engine problem).
(8) once you are satisfied with the above - you can NOW take it to the mechanic for the engine + tranny + suspension inspection. He won't find everything, but he will find the obvious. Take it to a mechanic EVEN if you are buying from a used car dealer. They cars are NO better than cars you buy from ebay and craigslist.com. Just more expensive.
1) Safety Ratings:
3) Fuel Economy: