The Signum is based on the Vectra and will complement the range when it arrives next May. It features a longer wheelbase than the Vectra and innovative rear seating arrangement, an aircraft-style 'travel assistant' which houses fold-out trays, a cold-storage box and a holder for a portable DVD player.
It will offer a new range of engines, including a 153bhp 2.2-litre direct injection petrol engine, a 173bhp 2.0-litre turbo plus a 175bhp 3.0-litre V6 common rail diesel.
Other features include adaptive forward lighting with bi-xenon headlamps - a steering-linked headlamp system that lights up bends in the road - and an orthopaedic air-conditioned driver's seat.
Vauxhall managing director Kevin Wale said: 'This car is tailor-made for demanding drivers who expect a lot in terms of dynamics, design, quality and presence and want to express their personalities and lifestyles. We're convinced the Signum will appeal to those who so far might not have considered buying a Vauxhall.'