I don't really know enough about the Insignia, is there an unbiased review of how it fairs against its main rival, the Mondeo?
To be fair I don't see there being much between the 2 engines but there seem more 118's available!
http://www.autoexpress.co.uk/carreviews/grouptests/230433/vauxhall_insignia_20_cdti_elite.html 
This. I haven't driven a 120d, but the 118d was pretty ****.[TW]Fox;18305188 said:Trust me, there is a difference. Test drive both.
I've had numerous 318d, 320d, 118d and 120d as loan cars and have racked up a few thousand miles in them - the x20d was ALWAYS the noticeably better choice.