I purchased three year old Peugeot 508 2.0 HDI 140 from a local dealer last week. It's generally in good condition, with 80,000 miles on the clock.

Having now done 500 or so miles I have noticed an occasional, but definite, 'stutter' or 'hesitation' between putting my foot down on the throttle and the car accelerating. If it was petrol I'd almost say a spark plug was occasionally failing to fire. Most noticeable at low speeds in second gear and at around 40-60 mph. What could be causing this?

Obviously, I'm going to book it back in with the supplier - but in expectation of the usual reply - "we cant find anything wrong with it" or "we can't replicate the problem" I was interested in your thoughts as to what the problem might be and my rights as a consumer should they fail to find the issue if it continues to occur.