1958 Pontiac Bonneville Series 25

The 1958 Pontiac Bonneville was big, bold, and came with all the hot engine options a buyer could ever want. It was a vehicle that could only have come from America, and it had a price tag that made it an exclusive car. The price and production were comparable to the Corvette and just 3,096 examples of the Bonneville Convertible were sold in 1958. A Tri-powered Bonneville Convertible was tasked with pacing the 1948 Indianapolis 500.

During the 1950s, the Pontiac evolved into a performance marque. By the close of the 1954 model year, Pontiac retired both its six- and straight-eight-cylinder engines. For 1955, all the cars in the lineup were powered by V8 overhead-valve power-plants that that shared some heritage with the small-block Chevy. In mid-year, a $35 Power Pack option added a four-barrel Rochester carburetor, which pushed horsepower to 200 on Hydra-Matic cars. For 1956, the engine was enlarged to 317 cubic inches, and a dual four-barrel carburetor option developed a hefty 285 brake horsepower. Only about 200 cars were so equipped. The 1957 model year brought another increase in displacement, this time to 347. A special Bonneville Convertible that used Rochester fuel injection was released in the Star Chief line. It was, however, not the most powerful 1957 Pontiac. In December 1956, a NASCAR Tri-Power option with three two-barrel carburetors was introduced.

For the 1958 cars, General Motors un-characteristically introduced new bodies and chassis. The Bonneville was made a separate series, one that was comprised of just two body styles - a convertible and a hardtop coupe. The standard engine was a 285–brake horsepower four-barrel V-8, but fuel injection and Tri-Power were still available. Performance enthusiasts generally opted for Tri-Power, which included three Rochester two-barrel carbs, 10.5:1 compression, and a high-lift camshaft.

Standard equipment included chrome wheel discs, special upholstery, and a Deluxe steering wheel.

by Daniel Vaughan | Oct 2017