The Opel Signum is a large front-engine, front-wheel drive, five-passenger, mid-size car manufactured and marketed by the German car manufacturer Opel from 2003 to 2008, exclusively over a single generation, derived from the Opel Vectra. Marketed almost exclusively in Europe, a rebadged Signum was marketed in the United Kingdom as the Vauxhall Signum. The Signum used the long wheelbase version of the GM Epsilon platform also used by the Opel Vectra Caravan.

The Opel Vectra is a mid-size car that was engineered and produced by the German automaker Opel from 1988 until 2010. Available in saloon, hatchback and estate body styles, the Vectra was also sold by the Vauxhall marque in the United Kingdom as the Vauxhall Cavalier from 1988 to 1995 and then as the Vauxhall Vectra from 1995 to 2008, and it was also sold by Holden in Australia as the Holden Vectra, by Chevrolet in Latin America as the Chevrolet Vectra.