Fig. 5From: Exhaust emission factors of greenhouse gases (GHGs) from European road vehiclesEffect of fuel/engine technology on the CH4 and N2O average emissions from L-category (top panels-a) and light-duty (bottom panels-b) vehicles. “Hybrid” category includes hybrid-gasoline vehicles. Kruskal–Wallis statistical test with ns: p > 0.05, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001Back to article page