The incorporation of regional EFs was key for improving accuracy of the estimated emissions of this category. CNG passenger cars accounted for 55% of CH4 and N2O emissions representing 10% of the total fleet. Emissions of diesel HDT were calculated using data with an important level of uncertainty, largely affecting the emission estimates of CO2,CH,NOx4and N2O emissions in terms of global warming potential (CO:1,CH4: 21 and N2, PM and SO
where HDT were responsible for 17%, 23%, 39% and 28% of total emissions respectively.