From Nookipedia, the Animal Crossing wiki
Gracie's car is the vehicle Gracie uses to flaunt the B.I.P. campaign in the Animal Crossing series. This event appears in Animal Crossing and Animal Crossing: Wild World. In Animal Crossing: Wild World, Gracie's car is yellow. Gracie will drive into town in her vintage car, sullying it, and the player will be asked to wash it. This task is performed by rapidly pressing 'A'. If done fast enough, the player will receive a piece of Gracie's clothing. If this task is performed moderately fast, the player will receive normal clothing. If the task is performed slowly, the player will receive nothing, and Gracie will be upset.
Gracie had it shipped from overseas and boasts that it has a "sultry silhouette."