On the Brougham production prototype, the so-called
"suicide" doors all latched into the body sill.
This arrangement was found to be unsatisfactory 

Contrary to the standard Cadillac models for 1957, the rear fender fins of the Brougham are swept backwards, as they had been on the Eldorado models of 1955 and 1956.  This novel fin line would become standard on the 1958 Cadillac models. Vertical tail-lamps are inset at the base of either fin. The rear bumper is in two parts set each side of the license plate holder. Incorporated at the outer edge of these bumper sections are the louvered exhaust ports.   Inboard are twin circular lamps, the outer pair (with red lenses) being the turn signal and brake lights, the inner pair (with white lenses) being the reversing lights.

The Eldorado Brougham’s parallel dual headlamps were introduced on La Espada and El Camino, two dream cars exhibited at the 1954 General Motors Motorama. Centered below each pair of headlamps is the distinctive grille masking the Brougham’s four, specially tuned horns

Like the prototype Eldorado Brougham, the production models too have exclusive, forged, alloy wheels combining aluminum and steel for strength and lightness. Their turbine-vane design differs from the saber-spoke design used on most of General Motors’ Motorama show cars. The central hub cap is removable, allowing access to the wheel mounting nuts; it sports the well-known Cadillac emblem in a harmonious balance of red and gold

The light-colored roof gives the Brougham an airy, convertible look.  It is made of brushed stainless steel and greatly enhances the beauty of the car. The extra-large tinted windshield has a compound curve for maximum visibility as well as filtration of the sun’s rays. The stainless steel grille at the base of the windshield supplies air for ventilation, heating and air-conditioning; In addition, an air outlet is recessed into the crown of each front fender to aid in cooling the engine compartment

No fewer than 44 interior trim and color combinations are offered, as are two different carpet styles Karakul, a close-knit wool loop carpet or mouton [French for sheep] which is a specially processed lambskin covering². Seat backs incorporate wide, comfortable armrests. A compartment in the rear seat armrest houses the following convenience items: a note-pad and propelling pencil, mirror and perfume atomizer containing an ounce of Lanvin’s renowned Arpège perfume extract. A heater located under the rear seat warms the rear compartment through special grilles at the base of the seat; these have individual controls

 

This is fashioned with a jeweler’s precision. All instruments are arranged for maximum driver convenience and there are warning lights and indicators for low oil pressure, low fuel level, high water temperature, battery discharge, hand brake left on, headlight high-beam on, turn signals and open trunk; the glove compartment is custom fitted with a cigarette case, tissue dispenser, a vanity compact, six magnetized drinking cups and an acrylic vanity mirror with a metal back, which folds out to form a tray for the cups; beauty is not all that makes the Cadillac Eldorado Brougham stand out from the rest of the luxury pack. It was also a bit of a mechanical marvel. Here are three key features. You will find more amazing facts in the following chapters.

 

According to the Cadillac Data Book for 1957, the Eldorado Brougham is powered by the finest, most powerful engine in Cadillac history. It develops its 325 hp through its two four-barrel carburetors, a larger capacity air intake and air cleaner, and a larger free-flow intake manifold.  Power is transmitted to the rear axle via the standard Cadillac Hydra-Matic transmission

 

The advantage of having air suspension [...when it works] is that the car remains level, and at the same height, irrespective of load and load distribution. The same, constant clearance is maintained between the rear axle and the frame, ensuring equal ride quality over smooth or rough road surfaces; it also prevents bottoming of the suspension and minimizes the lean of the car in curves; The system consists of individual air springs (or air domes) at each wheel, leveling valves at each wheel, an air storage tank and an electric air compressor which operates only when required and maintains a pressure of 100-120 lbs. per square inch in the air storage tank at all times

   
SAE brochure on the new, experimental air suspension system for the Eldorado Brougham