With all of the information about car buying available, you would think that people would know when to trade in a car. But, for the most part, they do not. Here is the absolute gospel. The best time to trade in a vehicle is at the end of a month (about three days before), because a dealer is looking to make a quota. So his car allotment won’t be cut, and his position for bragging rights won’t go down, either. Even better. If the month is ending a quarter, you can expect an even better deal. As dealers have to move product to keep their costs down and increase their position with their companies. Snowy or rainy days are good, too. The end of the month is also a good trade day, as there’s usually no business and dealers want to sell.