The Eldorado model was part of the Cadillac line from 1953 to 2002. The Cadillac Eldorado was the longest running American personal luxury car as it was the only one sold after the 1999 model year. Its main competitors included the Lincoln Mark Series and the lower-priced Buick Riviera.
For 1955, the Eldorado's body gained its own rear end styling with high, slender, pointed tailfins. These contrasted with the rather thick, bulbous fins which were common at the time and were an example of Eldorado once again pointing the way forward.
For 1956, a two-door hardtop coupe version appeared, called the Eldorado Seville.
1957 saw the Eldorado (in both Biarritz convertible and Seville hardtop bodystyles) with a revised rear-end design featuring a low, downswept fenderline capped by a pointed, in-board fin. The rear fenders were commonly referred to as "chipmunk cheeks". This concept was used for two years, but did not spawn any imitators.
Source: Wikipedia, 2011