Yes, I've been doing some research and have read the policy document etc. The only concern is that they have a clause specifying that they will not pay out for repairs if the claims inspector thinks the condition is pre-existing to the start of warranty cover.

Last night I read a very long thread of an Audi driver who had his head gasket blow shortly after taking out a Tesco warranty (including wear and tear). Audi stripped down the top end (at his cost, to be repaid by the warranty company if the claim was paid out), confirmed gasket failure and recommended replacement, head skim etc. Cost was about £1300 including the strip down. The warranty inspector said the cylinder was 'too clean' and that he suspected the gasket had failed before the warranty started. Tesco wouldn't pay out and he had to foot the bill himself. This is despite the Audi engineers insisting that the car was just serviced and failure had only just occurred, they disagreed with the inspectors opinion and said it was not unreasonable for the cylinder to be clean that quickly.

Difficult. The owner didn't attempt to get the SMMT or Financial Ombudsman involved which apparently helps a lot in cases like this.

It leaves me wondering if the X5 started to lurch, whether they would reasonably be able to claim it was pre-existing. I'm assuming that before making a claim the issue would be raised with BMW, diagnostics, software updates etc. In cases where software updates haven't stopped lurching the only other option I've seen discussed is tranny replacement which seems to have fixed the problem. You can bet at £4500 any warranty company will try to wriggle out of paying out initially. I wonder how helpful BMW would be in backing up a claim.

Your road tax is expensive! Over here it's based on CO2 output and the top band is £400 (yep my Boxster is in that group). Cars registered before 04/2006 drop down one group, that's why I'm looking at a pre-06 plate X5; the tax is only £200. Insurance isn't cheap here, my car is Group 19 (out of 20) and with 11 years driving and no claims or tickets I paid £900 last year plus £130 compulsory tracker subscription. With 17-mpg on premium unleaded from the Boxster, hopefully a diesel X5 will be a bit cheaper to run!