the side windows were painted in the color of the roof, or if the "Flo-tone" appearance was used, the color of the roof and lower body panels. The update brought several functional revisions, including a 12-volt electric system which allowed the installation of power operated accessories to be installed including air conditioning, standard dual exhaust to improve engine performance, and an automatic self-lubrication system (for the steering and front suspension). Mercury added its own version of the Ford Lifeguard safety system; a deep-dish steering wheel was standard, along with safety door locks, tubeless tires, and a breakaway safety glass rearview mirror. In addition, childproof rear door locks, seatbelts, and a padded dashboards were introduced as free-standing options. The 292 V8 was replaced by a 312 cubic-inch V8, producing 225 hp, while optionally available was a dual 4-barrel carburetor setup that provided starting in 1956. The 3-speed manual or the 3-speed Merc-O-Matic automatic transmission continued optionally, while an additional Touch-O-Matic overdrive was offered separately. Sun Valley For 1955, the Montclair model line offered the Sun Valley, succeeding the Monterey Sun Valley from 1954. In line with the Ford Fairlane Crown Victoria Skyliner, the front half of the roof was a tinted Plexiglas panel; in contrast to the Skyliner, the Sun Valley was a hardtop. While transparent roofs had been a styling feature of multiple 1950s concept cars (including the Lincoln Futura), the design as a production feature was not widely accepted by consumers, who found interior heat buildup in the vehicle during the summer unacceptable as air conditioning was not offered as a factory-supplied option until 1956. In total, only 1,787 Sun Valleys were produced. Second generation (1957-1958) For 1957, Mercury again revised its sedan line, with the Montclair becoming its mid-range offering, now slotted below the newly introduced Turnpike Cruiser. Mercurys grew in size, shifting to a 122-inch wheelbase, adopting a perimeter style frame, designed to accommodate a lower, wider body which allowed for a lower floor, and elevating all Mercury products above the new Edsel. The model line underwent a revision, as the Montclair four-door pillared sedan now shared its roofline with the Monterey. Alongside the two-door hardtop, a four-door hardtop was introduced, with both versions now designated as Montclair Phaetons; a Montclair convertible was offered. The 312 V8 was carried over from 1956, retuned to 255 hp. From the Turnpike Cruiser, the 368 cubic-inch V8 was offered as