I took one as a company car once. It is exactly the same to drive as a Vectra, with the same dash and driving position etc., just less practical.

The 3.0 CDTi V6 is an Isuzu engine and goes and sounds well. Didn't keep mine long enough to have any problems.

Mechanically, it's built on the Vectra estate floorpan so think of the Signum as that and you won't go wrong by looking for any troubles that afflict that car.

There's lots of legroom in the back because of the estate base, but the middle seat in the back is for small people for short journeys - and they will moan during the shortest of trips! And the boot is surprisingly small for such a big car.