As an IS250 owner (yes, who paid with his own money!) whos car does have some rattles and some excessive wind noise , I feel its worth adding that while it has been an annoyance, it has not spoiled my enjoyment of the car or made me regret buying it for one second.
For me, the good things about the IS250 far outweigh the teething problems Im having.
I should mention that my dealer has been on top of the issue from the first phone call I made to them. They've already made a 100 mile round trip to pick the car up and carry out an inspection and they will be making the same trip again, with a courtesy car for me to use, while they take my car for 2 days to carry out the required remedial work.
I know the IS250 is an expensive purchase and Lexus do trade on their reputation for quality and refinement but don't get too hung up about the rattles thing or you'll be driving around straining your hearing and getting suspicious of the least little sound instead of enjoying the ride :winky: