Q. Do diesel engines pollute more than petrol engines?
A. Diesel engines use less fuel and overall produce less CO2 than petrol engines. However, they produce more particulate matter and nitrogen oxides than petrol engines. Advanced technologies can improve the efficiency and cleanliness of both petrol and diesel engines. 

Mile for mile, diesel engines are more efficient as a power source than petrol engines. But this efficiency comes at a price. Diesel exhaust contains higher quantities of Particulate Matter (mostly consisting of un-burnt carbon compounds), as well as nitrogen oxide.

Over the years, Toyota has developed a number of engine technologies that lower diesel’s impact. Common Rail Diesel technology (D-4D), for example, reduces CO2 emissions. Special catalysts have been developed to reduce particulate matter and nitrogen oxides. Toyota's D-4D and exhaust gas recirculation help reduce the presence of hydrocarbons, carbon monoxide and particulate matter in vehicle exhaust.

In 2003, Toyota revolutionised the diesel engine by combining these different technologies into a single new integrated solution called Toyota Diesel Clean Advanced Technology (Toyota D-CAT). This advanced concept dramatically reduces particulate matter and nitrogen oxides resulting in the world’s cleanest diesel engine technology! In 2005, Toyota D-CAT was featured in a brand-new 2.2-litre high-power (177 DIN hp) diesel engine, built in Poland. Toyota’s new 2.0-litre D- D 125 diesel engine is available with a diesel particulate filter, reducing particulate emissions even further.

Toyota’s challenge is to ensure that diesel engines’ emissions performance is eventually equivalent to petrol engines.

The D-4D 2.2-litre, Toyota D-CAT engine integrates special technologies to produce very low NOx and particle emissions