Opel Signum Concept, 2001. A prototype for the production Signum which was supposed to introduce a new class of “flexible” large car and replace Opel’s previous (rear wheel drive) Omega large car range. The Signum used a long wheelbase version of the General Motors Epsilon platform. In the event although the Signum was admired for its space and practicality sales weren’t great and when the Insignia replaced the Vectra (on which the Signum was based) there was no equivalent model