Check for good heating and defrost systems

These are among the most important pieces of equipment on a beater, says Sarah Lee Marks, CEO of My Carlady, a car buyer's concierge service.
Marks says you should check the heater, battery, radiator, and front and rear defrosters for signs of aging or lackluster performance. These are the parts that are among the most vulnerable components to cold-weather failure.
A tip from Eric Brock, mechanic and car expert on JustAnswer.com: "If using the the defroster causes the windshield to mist over or you have a sweet smell when heat is on, the heater core is leaking and will require a major expense in repair, so stay away from vehicles that don't pass this test."