I work at a used car dealership...And honestly
You will do well to fix it and clean it well. Even though we work with cars everyday, the clean ones bring the most trade in value. believe it. We are human, and anything we don't have to do to a car to make it resellable is a plus for you. I appraise cars every day, and as I generally have an idea of what a car is worth before I walk around it...as I do, it goes up or down depending on condition, cleanliness, and overall time I have to put into it to get it ready to resell. We, like most people are in the business to make a living. I laugh when people come in thinking there car is worth $3000.00, then get pissed at me because I offer $1500.00 on trade, and their car is filthy, with bald tires and the CE light is on, and they haven't changed there oil in a year. A lot of people expect me to work for free then claim I am screwing them when they don't understand the time and effort it takes to get some cars ready. Yes we are in the business to make a money, aren't you? My advice, if you have the time, sell it yourself. You will always get more than you will trading it in, just as you will save money if you paint your own house. Don't have the time? Clean and fix it as best you can and you will get the most from it when you trade it in.