Check for oil burning, these motors are known to consume quite a bit of oil. Have the guy rev the car up and stand at the back. If it smokes blue then you'll know it burns oil. Black dots/soot on the rear bumper could also be another sign that it burns oil. Check if the gears shift smoothly with the car on and off. Check for rust. Check the trunk to see if there's a water leak there. Other than that, you should be good to go!