Opala 86

General Motors do Brasil was founded in January 1925 and for decades assembled and manufactured primarily light trucks and utilities. By the late 1960s the company elected to produce its first Brazilian-made passenger car. Deliberations weighed the larger American-style models already familiar to GM's global lineup against the lighter European Opel range already imported to Brazil in small numbers. GMB chose the mid-size Rekord/Commodore platform over the smaller Kadett.

On 23 November 1966, at a press conference at the Club Athletico Paulistano in São Paulo, GM publicly announced the project under the internal designation "Project 676." The name Opala — chosen from thousands of public suggestions, with a journalist's submission winning approval — may reference the opal gemstone, which is colourless when extracted but takes on multiple hues when exposed to light. GM has stated the name was not intended as a portmanteau of "Opel" and "Impala," despite the car's lineage from both.

The Opala was formally presented at the sixth São Paulo Auto Show on 23 November 1968 on a 16,140-square-foot rotating stand, with Stirling Moss among the celebrity guests. The launch range comprised a four-door sedan in Especial and Luxo trim levels. Styling adopted the "Coke Bottle" silhouette then fashionable on American performance cars including the Camaro and Corvette. Round headlamps, an egg-crate grille, and styling details borrowed from the 1968 Chevy II Nova distinguished the Opala visually from the European Rekord and Commodore on which it was mechanically based.

The original powertrain range offered two choices: a 153 cu in (2,512 cc) four-cylinder and a 230 cu in (3,768 cc) straight-six, both of GM North American origin. The straight-six featured seven main bearings, hydraulic valve lifters, and a reputation for durability and smoothness, though it suffered from an intake manifold design that distributed fuel mixture unevenly across cylinders. In 1971 a larger 250 cu in (4,093 cc) straight-six replaced the 3.8-litre unit. A performance variant designated 250-S was introduced in July 1974 following racing experience at the 24 Hours of Interlagos, where Bob Sharp and Jan Balder had finished second in an Opala and persuaded GMB to develop a more powerful engine option. The 4.1-litre six remained in production through to 1992 in both petrol and ethanol-fuelled variants.

With the 3.8-litre engine the Opala recorded a top speed of 112.5 mph (181.1 km/h) and reached 60 mph from rest in approximately 11 seconds, making it the fastest Brazilian car of its time before the Ford Maverick Dodge Dart's larger V8 displaced it.

GM manufactured approximately one million Opalas across its production life. Body styles included the four-door sedan, a pillarless hardtop coupé that remained in production well into the late 1980s long after American manufacturers had abandoned the style, and the Opala Caravan station wagon. Trim levels evolved over the years. In 1970 a more luxurious Comodoro variant was added, referencing the European Opel Commodore. An even more upmarket Diplomata followed in November 1979. An intermediate-grade Comodoro replaced the top-end position in 1980 when the Diplomata took the premium slot. The Opala SS was the first variant to receive a four-speed manual gearbox, paired with a tachometer and matte black paint striping.

Transmissions offered over the production run included three- and four-speed manual units with either column or floor-mounted shifters, a five-speed manual, and both three-speed and four-speed automatic gearboxes.

The Opala was a significant presence in Brazilian motorsport throughout the 1970s and 1980s. Its natural rival on the track was the Ford Maverick, which was powered by a larger-displacement engine. The introduction of the 250-S specification in 1974 restored competitive parity, and for years the contest between the Opala and the Maverick in endurance racing was decided largely by driver skill and pit crew efficiency rather than raw machinery. The straight-six's reliability and the availability of uprated intake manifolds made the Opala a practical base for stock car preparation.

The Opala was replaced by the Chevrolet Omega in 1992, itself an Opel-derived project, and the Opala's 4.1-litre engine continued in Omega production until 1998. Components and the chassis also found use in other Brazilian vehicles, including the Santa Matilde, Puma GTB, and the Fera XK. The Brazilian Federal Police operated Opalas for many years, and taxi drivers widely favoured the car for its reliability and easy maintenance. The pillarless coupé body style's survival in Brazilian production long after its disappearance elsewhere is one of the Opala's most distinctive footnotes in automotive history.