By 1955, the car line had proven itself and was allotted a special 270 horsepower engine, higher than the 250 offered in other Cadillacs that year. The 1955 Cadillac line may have resembled the 1953 and 1954 cars, but the Eldorado specifically gained longer, taller tailfins not shared with any other Cadillac that year. Sales increased to 3,950, and the price increased slightly to $6,286. 1956 cars included a new Eldorado Seville two-door hardtop coupe, which nearly outsold the convertible two-to-one. Once again, a special 305 horsepower was fitted to the Eldorados, whereas other Cadillacs had to make do with 285 hp. 1957 cars were entirely redesigned with a lower stance. Once again, the Eldorado possessed 325 hp vs. 300 hp for other Caddies. But the big Eldorado news for 1957 was the addition of a fabulously expensive four-door hardtop hand-built variant that cost an eye-watering $13,074. The price tag on the Eldorado Biarritz convertible was just $7,286. A two-door hardtop was also available. Exactly 400 four-door cars were built, and they featured rear-hinged rear doors and Cadillac’s first use of quad headlamps, a stainless steel roof and standard, but problematic, air suspension. It was also the first use of “memory” power seats. There were only minor changes for 1958, although 305 of the top-of-the-line Pininfarina-bodied four-door Eldorado Brougham were built and sold, again starting at $13,074. The Eldorado Seville two-door hardtop and Eldorado Biarritz two-door convertible each sold for $7,500. All cars but the Eldorado Biarritz featured the new front styling with quad headlamps that was unveiled a year earlier.