I have a 2009 Honda CR-V CDT-i with 60,000 miles on the clock. Under heavy acceleration there is black smoke out the exhaust - a fair amount. We have done 5000 miles in the five months since buying it and used one litre of oil. The Honda dealer says that they cannot find a problem. Once there has been some embarrassing black smoke, it seems fine and will not do it again. Under normal driving conditions it is fine. We live in Cornwall and spend a lot of time on country lanes, we only use the dual carriageways every few days. Should we be worried and asking for a proper diagnosis from the dealer? If so, I would think it was covered as it was reported to them within the three month warranty.