That, as several people have already pointed out, is a 1964 Superior-Pontiac Embassy limousine. Superior extended the heavy-duty Pontiac chassis used for all of its professional cars by 27-inches to obtain a wheelbase of 150-inches and hand-crafted the bodies and interiors for these vehicles which were promoted as being eight-passenger limousines and invalid cars. In 1964, the Embassy limousine retailed for $7,937. As available Superior-Pontiac model production breakdowns do not include the Embassy vehicles, it is unknown exactly how many of these were produced in total between 1962 (when production commenced) and the end of 1967 (when production ended) or for any given model year. However, it would be a safe bet that there were very few sold, built and delivered in any year. As such, I would say that this is a vehicle of considerable rarity.