I had an annual quote off BMW back in July but it was around the £670 mark. I did get a quote from LV and while I've heard they're a good company, they couldn't get under £558, still about £200 over the average I was being quoted. After cancelling the Sainsbury's policy and getting a few quotes, I went back to my original insurers and challenged their renewal premium of £399 and they immediately dropped it to £323 without any quibbling. I've got GAP insurance already but will probably save the extra couple of hundred quid and go with LV at the next renewal to be honest.
I know for a fact that Sainsbury's have got it wrong, but the thing is they almost certainly aren't using their own underwriting tables, they share them with a group of 'front' companies. You go and get online quotes from certain other companies and you'll see the exact same descriptions used for cars (and the exact same omission of the 328i Luxury Saloon). In fact the whole insurance business is very incestuous and a lot of the back-end administration is handled by a few large insurers - I used to work in the insurance business until I quit about 7 years ago, partly because I just don't like the way they operate. I could tell you stories that would make your teeth curl
The final straw was that Sainsbury's insist on charging me £26.50 for cancelling the policy... that they got wrong!
My demands on the phone for this to be waived were ignored and I was told to write in, which I have done, although I'm sure their first ploy will be to blow me off with some 'clause' or other, but I won't give up that easily - it's not the twenty six quid, it's the principle