Used Car Tip:Samarins.com offers a free printable checklist that lists a number of things to look for and ask auto dealers about. Among their suggestions: Ask auto dealers how many owners any used cars for sale have had, check if the car's exterior body lines match up for evidence of previous wrecks or body damage, and look under the hood of any used cars for sale for evidence of poor maintenance, including a dirty oil cap, corroded battery terminals or a burned oil smell when the engine runs.