1966 Pontiac Bonneville
8-cyl. 389cid/325hp 4bbl
With an experienced team and a lot of data.
By the mid-1960s, Pontiac was firmly in place as GM’s performance car division, and the Bonneville was Pontiac’s most powerful full-size model. The fourth generation of the car debuted in 1965, and the new generation was an evolutionary change from the 1964 model year. A variety of bodies were once again available, including a 2-door or 4-door hardtop, a 2-door convertible, and a 4-door station wagon. Interiors were an upgraded version of the Pontiac Star Chief interior of the same year, adding padded surfaces, courtesy lights, and upgraded cloth or vinyl upholstery options.
Under the hood, the 1965 Bonneville featured a 389-c.i. V-8 engine at 333 horsepower with the 3-speed or 4-speed manual transmission, and 325 with the Hydramatic automatic transmission.
For 1966, the Bonneville hardly changed at all, but in 1967 the engine shifted to a 400-c.i. plant that produced the same horsepower numbers. However, several versions of a high-output 428-c.i. V-8 were also available, yielding up to 390 horsepower. The 1967 model year also saw the end of the trademark mid-19960s Pontiac split grille, with the car’s new face being much less imposing with de-emphasized headlights.
A 4-door sedan was introduced to the Bonneville line in 1968, along with further upgrades to interior luxury. The bodywork became sleeker and the headlights were now side-by-side instead of stacked. Base engine horsepower was increased to 340 from the 400-c.i. engine at 10.5:1 compression when paired with the new Turbo-Hydramatic transmission. However, manual transmission Bonnevilles came with the same 8.6:1 engine at just 265 horsepower.
Bonneville buyers in 1969 found another horsepower increase waiting – up to 360 for the new year, which made the 390-hp 428 almost superfluous, unless you got the close-ratio 4-speed manual transmission and limited-slip Safe-T-Track rear axle. In 1970, the Bonneville got an engine upgrade to a 10.75:1 compression 455-c.i. V-8 at 360 horsepower (or 370 in the station wagon).
Collectors will want to keep on the lookout for Bonnevilles with the 428-c.i. engine, synchromesh 4-speed transmissions, and the Safe-T-Track limited-slip differentials. Or, just look for a 1969 model in good condition. However, the earlier years of this generation will have plenty of upside potential due to the more attractive bodywork. For an interesting trivia win and conversation starter, Canadian versions of the Bonneville were known as “Parisienne” throughout this era.