Builders and designers played into the diner owners' competitive spirit, advertising the latest models on a regular basis. Diners were marketed almost like cars, with new models continually being introduced so that owners would trade in for bigger and better units. Diner interiors, many exposed to 24-hour wear and tear, were renovated out of necessity. One company, Erfed Corporation, of Rutherford, New jersey, specialized in the modernization, on site, of tired diners. Many older diners were traded in for new ones; the old diners were then spruced up and resold by the manufacturer.