Lowriders are riding high. For instance, the Petersen Automotive Museum in Los Angeles recently opened an exhibition titled "La Vida Lowrider: Cruising the City of Angels." It includes 21 cars, several bicycles, pedal cars, scale models, photographs and other images from the lowrider culture of Los Angeles. This is not the museum's first exploration of the subject. In 2000, it held a show called "Arte y Estilo: The Lowriding Tradition." "We always thought about revisiting the subject," said