I own a 1997 W202 Mercedes-Benz C180 Elegance Automatic, which has covered 115,085 miles since new, and has a Full MBSH, and is shortly due in 3,000 miles to have the large ‘B’ Service carried out by Mercedes-Benz of Worcester. I have noticed recently, that on mild acceleration from standstill and also on the move that the engine is ‘pinking’ mildly, and was wondering whether this is due to "Tesco Unleaded 95 Ron Fuel", without traditional detergents, or Incorrect Ignition Timing, or possibly worn Inlet/Exhaust Valves, although it is returning overall 38mpg which is excellent for a car of this vintage and mileage. The car is only driven at 60mph daily on motorways in the main on Cruise Control. The engine only uses half a litre of engine oil between 10,000-mile service intervals, and does not emit any clouds of black exhaust smoke on acceleration or deceleration. Please could you send me your best advice on how to overcome this problem? Should I purchase fuel from traditional petrol stations e.g Texaco, Shell, Esso, BP instead? Does the cylinder head need to be removed, to decarbonise the ports and fit new Inlet and Exhaust Valves. In my opinion at any rate, I would say that the W202 MB C Class was always under-estimated for its longevity and reliability, and build quality, and offers excellent prestige executive motoring.