From Wikipedia:
Opel Commodore C (1977-1982)
Opel Commodore C
The Commodore C was introduced in late 1977, at the same time as the Rekord E. The Commodore continued to be a larger and more luxurious version of the Rekord, but was available only as a saloon with a more conservative and boxy design, following the European trend of the time. There was no Coupé version of the Commodore C, as it was replaced by the Monza, which was instead sold as a Coupé version of the Senator. The single engine used by the Commodore was the straight-6 2.5 L.
The new model featured a similar front end to the larger Senator. It was sold in the UK under the name Vauxhall Viceroy, which was a larger and more luxurious version of the Carlton. It was the Opel Commodore and Vauxhall Viceroy that formed the basis for the first Holden Commodore in Australia, and was sold in South Africa as the Chevrolet Commodore until 1982, when it was rebadged as an Opel. There was an estate version (dubbed the 'Voyage' in Germany) that was offered in the Opel range from 1979 to 1982 but was never offered in the UK as a Vauxhall Viceroy. This estate, however, became a mainstay in the Holden range in Australia, and was also available in the Chevrolet range in South Africa.
The Commodore was dropped by GM in Europe and absorbed into the Opel Rekord range of 1983. However, in South Africa, Delta (formerly General Motors South Africa) offered a revised version of the Commodore until the early 1990s, again combining the bodyshell of the Rekord with the front end of the revised Senator, which was not sold in that country. A similar model, the Royale, was also produced by Daewoo in South Korea.
It is this model which the early Holden Commodore models were based on, introduced in late 1978, and eventually replaced (after several facelifts) in 1988, with a model based on the Senator.
[edit] Trivia
A one-off Vauxhall Viceroy estate car was built in 1981 for Queen Elizabeth II, for her to carry her Corgi dogs. The car still survives today.
As of 2006, there are now only 15 Vauxhall Viceroys left registered in the UK.