For 1958, Chevrolet models were redesigned longer, lower, and heavier than their 1957 predecessors, and the first ever production Chevrolet big block V8, the 348 cu in (5,700 cc), was now an option. The Bel Air gained a halo vehicle in 1958, the Impala, available only as a hardtop coupe and convertible in its introductory year. Impala styling followed the basic lines of the other Chevrolet models but received special styling cues including a different roof line, a vent above the rear window, unique side trim, and triple tail lights housed in slightly broader alcoves. For the budget conscious, the Biscayne, (formerly the 210) and the Delray (formerly the 150) completed this model year's family-oriented and utility offerings.
Chevrolet's design for the year fared better than its other GM offerings, and lacked the overabundance of chrome found on Pontiacs, Oldsmobiles, Buicks and Cadillacs. Complementing Chevrolet's front design was a broad grille and quad headlights that helped simulate a 'Baby Cadillac'; the tail received a fan-shaped alcove on both side panels, which housed dual tail lights. Despite being a recession year, consumers made Chevrolet the No. 1 make of automobile (beating Ford, which held the title in 1957) and the Bel Air was at the core of Chevrolet's popularity. With its wide variety of body styles and models, Bel Airs could be optioned with almost every conceivable luxury within the Chevrolet line. The Nomad station wagon name also reappeared in 1958 when the vehicle bowed as the premium four-door Chevrolet station wagon, lacking the unique styling of the 1955-57 Nomads. Most Chevrolet station wagon models had two tail lights housed in abbreviated alcoves, which were made smaller to accommodate the rear gate. A new dash was used.
Source: Wikipedia (original)