Arizona

16-17 January 2014

Previous Next

Lot 80

1958 Pontiac Bonneville 'Tri-Power' Convertible

  • Chassis no. P558H1045

Sold for $99,000


300 bhp, 370 cu. in. OHV V-8, triple two-barrel Rochester carburetors with vacuum linkage, Strato-Flight four-speed Hydra-Matic automatic transmission, independent front suspension with unequal length A-arms and coil springs, live rear axle with coil springs, and four-wheel power drum brakes. Wheelbase: 122 in.

  • AACA Senior National First Prize winner
  • Desirable 300-horsepower Tri-Power engine
  • An outstanding highway cruiser


You don’t have to know anything about a ’58 Bonneville Convertible to appreciate it. It is a car that could only have come from America; it was 211 inches and 4,040 pounds of steel and chrome, and it had all of the hot engine options you could ever want. In its first year of having its own line of cars, Bonneville was among the hottest cars in the red-hot GM lineup, and a Tri-Power Bonneville Convertible paced the 1958 Indianapolis 500. It was an expensive and exclusive car, though—both price and production were comparable to Corvette—and only 3,096 convertibles sold that first year.



Beyond the styling, Pontiac was a high-performance engine company with its own unique offerings. The 370-cubic inch V-8 was overbuilt, dependable, and supremely powerful, especially with the Tri-Power/Hydra-Matic transmission combination, which yielded 300 horsepower, thanks to 10.5:1 compression and a high-lift cam. Hot Rod tested a Tri-Power sedan in 1958, and they found that it was capable of 60 mph in 7.6 seconds, but the convertible does weighs about 200 pounds more than the sedan, so it would be a second or two slower. (As few enthusiasts today are buying Bonnevilles to win drag races, it’s an easy trade-off to make for convertible style.) A Rochester fuel-injection setup that was rated at 310 horsepower was also available, but in testing, Motor Trend found that the Tri-Power was actually faster and, of course, much less trouble.



Restorations of 1958 Bonneville Convertibles are difficult and expensive, as supplies of NOS parts and parts cars are both highly limited. Fortunately, this car has not only had an amazingly well-preserved restoration, but the consignor has also ensured that it is in top running condition. The carburetors are freshly tuned, and a new top and wide whitewall radial tires complement the interior work, which includes new color-keyed belts. A recent all-day rally has demonstrated the car’s ability to run at freeway speeds without difficulty. In fact, this car would not be available if the consignor did not think it was too nice to be exposed to the salt air of his beachfront home.



Any fan of the Bonneville Convertible knows that Tri-Power ’58s seldom trade hands. Finding one ready to drive or show, with all needs attended to, is an annual event at best.

Please contact our exclusive automotive transportation partner, Reliable Carriers, for a shipping quote or any other information on the transport of this vehicle.

Alexander Weaver

aweaver@rmsothebys.com

+1 864 313 6844
California, United States

Alexander Weaver joined RM Sotheby’s in 2011 as a Car Specialist after graduating from Furman University in South Carolina. Born... read more

Augustin Sabatié-Garat

asabatie-garat@rmsothebys.com

+44 (0) 74 1511 4179
United Kingdom

Augustin Sabatié-Garat joined RM Europe in 2012 as a Car Specialist after more than a decade in the collector car hobby. Gradua... read more

Barney Ruprecht

bruprecht@rmsothebys.com

+1 203 912 7168
Ontario, Canada

Barney’s interest in classic cars began at an early age after being introduced to his father’s all-original 1965 Porsche 9... read more

David Swig

dswig@rmsothebys.com

+1 415 302 2247
California, United States

David Swig joined RM Sotheby’s West Coast division as a Car Specialist in May 2015. He is a life-long automobile enthusiast and ... read more

Don Rose

drose@rmsothebys.com

+1 617 513 0388
United States

Don joined RM in 2006 after several years of professionally trading sports and classic cars, and after earning a reputation as a noted... read more

Donnie Gould

dgould@rmsothebys.com

+1 954 566 2209
Florida, United States

Donnie Gould joined the RM team in 2002 as a partner and Car Specialist after more than two decades in the vintage automobile auction ... read more

Gord Duff

gduff@rmsothebys.com

+1 519 352 4575
Ontario, Canada

Gord Duff began his journey with RM Sotheby’s in 1998. Since then, he has gained an intimate knowledge of a variety of marques a... read more

Ian Kelleher

ikelleher@rmsothebys.com

+1 310 559 4575
California, United States

Ian Kelleher began his automotive career immediately following his graduation from Oberlin College with a Bachelor of Arts in Politica... read more

Jake Auerbach

jauerbach@rmsothebys.com

+1 310 559 4575
California, United States

Jake Auerbach got his start in the automotive industry at an early age, spending his summers during high school working at a classic c... read more

Jonathan Sierakowski

jonathan@rmsothebys.com

+1 519 352 4575
Ontario, Canada

Jonathan Sierakowski developed a passion for classic cars while working at a Connecticut restoration shop as a teenager. He graduated with a... read more

Kurt Forry

kforry@rmsothebys.com

+1 717 623 1638
California, United States

Having worked for Bonhams’ Automobilia department for over 10 years, Kurt Forry joined RM Sotheby’s with more than a decad... read more

Matt Malamut

mmalamut@rmsothebys.com

+1 805 231 6410
California, United States

A long-time car enthusiast and Southern California native, Matt studied Automotive Technology at San Diego Miramar College and complet... read more

Michael Squire

msquire@rmsothebys.com

+44 (0) 20 7851 7070
United Kingdom

Michael Squire joined RM Sotheby’s European Division in the summer of 2016. He comes to RM with a prestigious racing background ... read more

Mike Fairbairn

mfairbairn@rmsothebys.com

+1 519 352 4575
Ontario, Canada

As one of the three founding partners of RM Sotheby’s, Mike has a long-standing interest in the classic car industry. Graduating... read more

Oliver Camelin

ocamelin@rmsothebys.com

+44 (0) 75 0110 7447
United Kingdom

With an extensive background in exotic sports car history and sales, a particular passion for American curves, and fluency in three la... read more

Paul Darvill

pdarvill@rmsothebys.com

+44 (0) 20 7851 7070
United Kingdom

Paul Darvill joined the RM Sotheby’s European team at the beginning of 2015. Paul holds a degree in French and Politics from the... read more

Pete Fisher

pfisher@rmsothebys.com

+1 519 784 9300
Ontario, Canada

Pete Fisher was first introduced to antique cars in high school, working for Classic Coachworks in his hometown of Blenheim, Ontario. He att... read more

Peter Wallman

pwallman@rmsothebys.com

+44 (0) 20 7851 7070
United Kingdom

Peter Wallman joined RM Europe in 2007 following nearly two decades in the international advertising industry, where he was based out ... read more

Shelby Myers

smyers@rmsothebys.com

+1 310 559 4575
California, United States

Shelby Myers grew up with the classic car industry infused into every aspect of his life. He had the unique opportunity to watch the R... read more

Tonnie Van der Velden

tvandervelden@rmsothebys.com

+31 653 84 19 60
United Kingdom

Tonnie Van der Velden joined RM Sotheby’s European division in September 2015 as a Car Specialist. A lifelong enthusiast, Tonnie... read more