When the hybrid batteries failed in my 2007 RX400h in February 2014, the view of Lexus Twickenham was that complete replacement was required.
I wanted a second opinion (indeed I posted on here asking for recommendations: Boxbrownie was kind enough to help). With the prior blessing of Lexus Head Office Customer Care I had the car moved on a low loader at my sole expense to Lexus Edgware Road. Their diagnosis was identical to Lexus Twickenham, and indeed they carried out the work. The car was off the road for a week or so, and the bill was £2637.34 (plus the cost of the low loader, and a hire car throughout the time my car was off the road).
I had contacted Lexus head office before and after the battery replacement, and I understand Lexus Edgware Road did as well.
The response of Lexus was:
"I was sorry to learn of the diagnosis from Lexus Edgware Road. Please accept my sincere apologies for the disappointment this has caused. Naturally, we hope that our customers will not experience any problems with their vehicles. I regret this has not been the case. We rigorously test every aspect of the car before production commences. However, we sometimes have to react to unforeseen difficulties as they occur and, regrettably, we cannot guarantee that a part will not fail unexpectedly. At the end of the warranty period we encourage our customers to invest in an extended warranty for further peace of mind. For those who do not choose this option, we do try to provide an out of warranty goodwill contribution where possible. Unfortunately, we cannot offer this support indefinitely and I regret to advise you we are unable to offer a contribution towards repairs costs on this occasion. I am sorry we are unable to respond in a more positive manner and I realise our response will come as a further disappointment to you. For this I can only apologise."
Now of course I do not expect an indefinite warranty. However this was a relatively low-mileage car, owned by me from brand new, and serviced to exact Lexus' specification. At the least I would have expected curiosity into the problem from Lexus, if not a contribution to the expense, especially if this is a risk as microscopic as Colin Barber suggests.