To make sure you get the best possible trade-in value, keeping your car in the best condition is one of the biggest factors when trying to receive the largest valuation. Aside from how great your car looks inside and out, the actual make, model, trim, age, mileage of your car and added accessories will influence the value of your car. Also, keep in mind that the value of your trade-in can fluctuate as the car market conditions change as well as what zip code you are located in.