Inspecting the fuel lines
This has to be one of the most overlooked areas of a used car. To do this you'll want to get under the vehicle and locate the fuel tank (most likely towards the back of the vehicle), and find either some rubber hoses coming from the tank, or some small metal pipes coming from the fuel tank. Follow these up until they go into the engine, looking for damage or excessive wear as you go along (rubber: any cracks or brittle tubing ; metal: any bends in the pipes). If you run into a canister of some sort, that is the fuel filter, and it is a good idea to ask when the last time it was replaced (if the car has more than 100,000 miles on the car)

