I know Clarkson hates Vectras, but, Top gear did a test of the Vectra VXR a while back, Clarkson loved it, but he said it was the worst handeling car he had driven, the understear was huge, In the footage it was just going in a straight line when he tried to turn a corner at speed.
A collegue of mine had a vectra C SRi as a hire care and he didnt rate the handeling either.
I used to own a Vectra B 150 SRi and I had no complaints regarding the handeling.
Try www.vvoc.cpm for more vectra help
HTH
Paul