Is this a DPF issue ?
I've owned my 2007 159 2.4 diesel for over 3 months now and all has been well apart from an issue that has just started.
On the motorway last week, the car started to shudder and instant mpg dropped to early 20's, the car wouldn't accelerate well at all. This went on for about 10 miles or so then settled down. I put it down to the DPF doing a regen (First time I've noticed it happen since I've had the car, 4,000 miles, mixture of local and motorway journeys).
Since then, the car has been fine apart from when light pressure is applied to the throttle pedal when the car seems a bit juddery, its as if it is missing. My drive into work involves a stretch of 40 mph dual carriageway and sat in 4th at 45-50 with hardly any pressure on the throttle you can feel the judder, its not a major judder (not like being in too low a gear) but noticeable all the same. Had a similar problem in a Mercedes a few years ago and that was a throttle linkage issue.
Any ideas at all ? The car is in next week for cam belt/water pump so if it is the DPF I can get them to look at it & also look at getting the DPF removed!