I agree completely, it should be completely transparent. Insurers are alway completely opaque in how they come up with premiums. The truth is a lot more complicated. The basic underwriting premise used is about inherent risk. This can be the car (try insuring a Subaru Impreza I), the driver (points/drink driving/age/experience), claims history (more than three claims in three years) and location (if you live in Manchester/Liverpool/London or the most expensive place to insure; Birmingham). All these factors have a bearing on premium and then no-claims bonus reduces it. Unfortunately, investment returns from premiums has dropped. This, along with the increase in the Ogden Rate, have further increased premiums when you would expect them to drop.