As with any used car purchase, check for fluid leaks before and after driving it. With a Cobalt and it’s associated recall for gas leaks, after driving check for gasoline odors in front and behind the drivers and passengers rear wheels, set the parking brake and out of gear and running while doing this, also look underneath for dripping gasoline.
When test driving accelerate to highway speed 65 or faster and radio off, you are checking for wobble, vibrations & unusual noises from the front end. Also drake hard at speed to see if your front discs are warped or suspension vibrates.
In a empty parking lot and at a safe speed do a steering wheel stop to stop (completely to one side then the other)
There should be no clunks, sticky spots or weird things happening. Check the air conditioning, heater and blower for functioning, when you first turn the key on with out stating you should not hear a clunk, clunk, clunk...... sounded you do it has a bad HVAC damper door motor driver, this is an expensive repair.
Check for loose and or miss-aligned front clips or rear plastic panels, an indication of a self repaired accident.
There are a multitude of other thing to check, and I am sure someone else will mention them.
And always remember “Let the buyer beware”.
And get any verbal Guarantee in writing and ask for any receipts for “replaced parts”.
