Anne,You are talking about the LA parade phaeton, which is actually a 1952 that was updated by the factory in 1955. http://www.imperialclub.com/Rare/Phaetons/1950s/article.htm It is an open car, but can't be considered a convertible since it doesn't have a top at all. It is one of three, originally residing in New York City, Chicago and Los Angeles. I believe the Chicago car made it's way to a museum in Las Vegas.Roy67 Crown FDHTIn a message dated 7/11/2005 10:53:42 PM Pacific Daylight Time, lanikai146@xxxxxxxxx writes:Every Hollywood Parade the Mayor rides in a 1956 White Imperial Convertible with even the Presidental flags attached.....I have watched this car for over 29 years....Anne......Classic car lady........movie cars.....Lucy and Ethel....1956 Southamptons....Coupe in Desert rose and white top.....Ethel....Sedan....in Powder Blue and white top