I have a 2008 Jaguar XF 2.7 diesel Premium Luxury that I bought as a Jaguar approved used car from a main dealer three months ago. It came with a full warranty and has done 58,000 miles. I regularly (once a week average) do runs of 100 miles or more, and always have normal (urban) speed running for five miles or so at the end of them. I don't know its regime prior to my purchase but I was assured it was checked by the dealer as part of the approval scheme.

I have recently noticed that on starting the engine I can smell a sooty odour in the passenger compartment for about a minute, that then disappears. Twice recently it has failed to start properly but has responded OK after a few seconds delay and another press of the starter. Please can you tell me if these are symptoms of something expensive about to go wrong - or worse still having already gone wrong.