A vehicle includes a frame, front and rear wheels, a motor, and a driver seat. A passenger seat disposed side-by-side with the driver seat has a seat base that is pivotable about a horizontal pivot axis between a seating position where it extends horizontally and a storage position. A retaining surface having a seating position groove and a storage position groove is fixed with respect to one of the seat base and the frame. A retaining member fixed with respect to another of the seat base and the frame is complementary to the grooves. The retaining member is received in the storage position groove when the seat base is in the storage position, thereby retaining the seat base in the storage position. The retaining member is received in the seating position groove when the seat base is in the seating position, thereby retaining the seat base in the seating position.