This paper collected real-world fuel consumption and emission data for two diesel vehicles with and without the installation of the Diesel Particulate Filter (DPF) using the portable emission measurement system (PEMS). It compared and analyzed the characteristics of the fuel consumption and emissions, as well as the fuel consumption and emissions at different speeds, accelerations, and decelerations for before- versus after-installation of DPF. It further analyzed the distributions of the corresponding fuel consumption and emission rates. The comparison results shown that DPF could considerably reduce particulates and CO emissions, in which PM for the two tested vehicles was reduced by 98% and 91%, and CO was reduced by 94% and 60% respectively. For both before- and after- the installation of DPF, the fuel consumption rates in L/h and emission rates in g/s increased with the increase of speed and acceleration, in which high fuel consumption and emission rates were concentrated in the region where both speed and acceleration were high. It is also found that the fuel consumption factor in L/100km and emission factors in g/km decreased with the increase of speed, but increased with the increase of acceleration. The maximum emission reduction by DPF occurred at the high speed region.