Hi all, purchased my first ever X5 for the missus last week. 54 plate 4.4 Auto, well pleased. I based it on owning a couple of 540i saloons a few years ago and took the plunge. Got a couple of niggles which I think I am sort of on top of with the superb help of the posts on the forum. But one which I need a little direction please .......... I am having the Auto box fluid and filter changed in the week, cos I have noticed a slight 'lunge' issue between 1st and 2 nd especially noticeable when cold. Specialists are also going to upload all latest software etc etc. But I have noticed, what I can only describe as a deep drone noise which, doing my best to describe, shows itself typically when you are maybe in a gear that is perhaps slightly too high for the speed, typically 57-60mph in 6th and you accelerate a little, but,not enough for the car to change down. It seems that you get a deep drone, that I can feel through the pedal, that disappears when you accelerate that bit harder and the car changes down ??? Is it gearbox linked, or was maybe thinking diffs, after reading some other posts. A bit of direction for a novice would be greatly appreciated, Thankyou, Trev.