According to Jim S02 E02 Cars and Chicks

Jim claims women aren't capable of getting a good deal on a car, and prophetically, when Cheryl helps Dana buy a new car, it turns out to be a lemon. Dana begs Jim to use his macho influence at the dealership to help her, but instead he allows sexy sales manager Gretchen to talk him into trading the family van in for a sports car — without consulting Cheryl.