Yes, but what about the emissions from the massive diesels used in ships , some of which are many years old ?? They are much worse offenders , emitting long trails of dark smoke for MILES behind them. I went on two this year ; MV Discovery and MV Funchal . Neither are in the first flush of youth, and Funchal struggled to get to her destination due to strong winds and adverse currents ; the noise aft from her funnel exhausts was APPALLING and people got "smuts" in their eyes.However, I did see some really modern cruise ships in various ports,and they seemed to have virtually no emissions at all ! Progress ??
As to cars ; we have a 1.6 litre Peugeot diesel estate , which gives VERY good mileage per gallon and we'd hate to lose it !!