When you are ready to sell or trade in your car, your main goal is to get the most you can for it. There are four areas you need to consider: how it looks inside and outside, how it works, and its service history. At this point there’s nothing much you can do about the service history that you haven’t already done. Hopefully you’ve been conscientious about having it serviced regularly, and keeping your receipts. If not, don’t worry. Just dig out what you have, and make a vow to be more careful with your new one. Showing prospective buyers…