The Tri-Power Bonneville convertible was hot enough to be
named the 1958 Indianapolis 500 Pace Car.
The 1958 Pontiac had an aircraft look and all 16 models carried “guided-missile” side trim and “jet-pod” rear fenders. “It’s a wholly new car, with nothing left over from ’57 except the wheels,” said Motor Trend.
And it was. The cars were longer and lower looking, with a new honeycomb grille, dual headlamps, dual tail lamps and a new series Bonneville. A stronger tubular X frame allowed lower recessed floors. A new ball-joint suspension was used up front and optional “Ever-Level” rear air suspension was available. A Safe-T-Track no-spin differential added $54 to the Pontiac’s price.
“Bonneville” became the name of a line instead of a single model in 1958. A convertible and sport coupe were offered. Base powerplant was the Star Chief V-8. Both models used the shorter Chieftain wheelbase, but with a special longer, ribbed rear deck lid also used on Chieftain convertibles. There were “Bonneville” fender scripts and hood and deck lettering, four chevrons on the lower front fenders, four stars on the rear fenders and rocket-shaped, ribbed semi-cylindrical moldings on the “guided missiles.”
Standard equipment included a Deluxe steering wheel, chrome wheel discs and special upholstery. The Bonneville coupe sold for $3,481 and the convertible was $3,586. Pontiac built 9,144 hardtops and 3,096 convertibles.
New options included a deluxe Electromatic radio and, for Bonnevilles, bucket seats. Tri-Power carburetion on standard blocks was $93.50 on Bonnevilles. The “standard” Tri-Power setup used three two-barrel Rochester carburetors, 10.5:1 cylinder heads and a high-lift camshaft for 300 hp at 4600 rpm. Rochester fuel-injection was a $500 option. This setup included 10.5:1 compression ratio cylinder heads and gave 310 hp at 4800 rpm. Pontiac experts believe that 200 Bonnevilles carried this option. A Bonneville hardtop with the 300-hp engine was road tested by a magazine. Zero-to-60 mph took 7.6 seconds and the quarter-mile took 16 seconds.
In March 1958, two NASCAR-certified “extra hp” (Tempest 395-A) V-8s were released. The “PK” option was $233 on Bonnevilles. It included a four-barrel carburetor, 10.5:1 cylinder heads, higher-lift camshaft, low-restriction dual exhausts and other special components good for 315 hp. The “PM” option was $331 on lower-priced lines and $320 on upper lines and it combined special high-performance hardware with Tri-Power induction to generate 330 hp.
To celebrate General Motors’ 50th anniversary, a Tri-Power Bonneville convertible was picked to be the Official Pace Car for the Indy 500 race in May 1958.
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