I have a 2013 xf 3.0 D with 48200 miles on the clock. My question is when at normal operating temp and pull up, say for lights or a queue of traffic and whilst still in 'D' I notice a slight grumbling noise this eases off if I put the car in 'N' or 'P'. I've only just started to notice this noise and was wondering if this is the forebear of a problem with the autobox? By the way I always switch the S/S off and no warnings have appeared on the dash regarding any sort of fault at all.