The D-528 was built to test advanced concepts in seating, lighting, air conditioning, and front frame design. The hinged rear fender bulges were functional, concealing a spare tire on one side and a gas tank on the other. Such a design gave the car adequate luggage capacity despite the need to accommodate a large air conditioning system. Although it boasted design features such as a pillarless windshield and Ford’s first reverse-sloping retractable rear window, it was an in-house research vehicle that was never shown publicly. “Beldone” was a stage name selected by Paramount Pictures for the car’s appearance in the 1964 Jerry Lewis movie, The Patsy, not an official Ford designation.