Driving 200 mile journey (W203 auto 45K C200cdi 2004) notice fuel consumption is around 5mpg lower than normal no other probs, drive around locally for 3 days no probs. Set off home today and after around 40 mles no power and no kick down will change down ok on tiptronic but low power (struggling uphill at 55mph) then masssive cloud of black smoke. Pull in at services, prat around with MAS MAF (ie disconnect and tap a few times) or whatever its called. Restart and continue journey with no probs until about 5 miles from home and then same again. Ive done millions of miles in other cars golfs, vectras, mondeos, escorts etc never had any probs. Buy myself a "reliable" merc because of miles I do and no end of probs sureley for a component failure (reading other threads its not uncommon) to cause this after so few miles then the car is not "fit for purpose". Any comments/help would be greatly appreciated.