It has been widely known that diesel-powered cars generate lower greenhouse gases compared to petrol/gasoline cars. Contrary to this, a study conducted by Transport and Environment (T&E) claims that on the basis of their full lifetime, diesel cars generate more air particulates, carbon dioxide, and NOx than those powered by petrol or gasoline.
In their full lifetime, diesel cars could emit 3.65 tons more carbon dioxide than petrol/gasoline cars. How this result was obtained by T&E was provided by the Green Car Congress, by explaining the assumptions as follows:
“The average gasoline lifetime driving distance of 175,000 km is taken as the starting point. The average diesel car is driven longer, T&E adds an additional 7000 km to the diesel lifetime distance to account for this. T&E used the latest real-world fuel consumption figures for diesel and gasoline: 6.3 l/100 km and 7.1 l/100 km, respectively. To account for biodiesel effects, T&E assumed a conservative estimate of 5% biodiesel content.”
The probable reasons for the diesel cars’ higher greenhouse gases emissions are: their engines are heavier and more complex, their fuel refining process is more energy-intensive, their mileage counts are higher because of lower fuel costs, and the addition of biodiesel in blended fuels.