can some body explain how a vectra c sri 1.9 cdti estate 120 is more than . vectra c gsi 3.2 v6 group 15 my insurance is £450.00 100.00 pounds more than last year,i got full no claims as well.i was qouted for the estate sri 120 £750.80,how the hell did they work that out and that was on confused.com ,and that was the cheapest.checked my car again and it came in with in £10 differance that was the 3.2 v6????????????????