The miles are a moot point unless the lower Mile one has a drive unit issue hence the lower miles. When you drive them come to a complete stop all radio and heater/ac off windows up and floor it. Listen for a milling noise which will be noticeably different than the regular sound the drive unit will make. Remember, which ever one you choose you will still have 8 year unlimited mileage warranty on drive unit and battery so if there is an issue tesla should replace it at no cost.