Particle size distribution and particle number concentration from diesel engines are subjects of significant environmental concerns especially in the EU. A few years ago, the UN-ECE PMP proposed a method for measuring particle emissions in the diluted exhaust of internal combustion engine vehicles, which has become a key method used in new dilution systems and sampling condition. This paper describes the effects of parameters such as condensation particle counter (CPC) according to test procedures, test fuel and vehicle test mode, including NEDC and CVS-75 mode. The main results obtained from this study can be summarized as follows: (1) Periodic calibration of the CPC system is essential because the long-term usage of a CPC leads to an underestimation in the measurements of small particles. (2) Particle emissions measured by the UN-ECE PMP method were found to exhibit comparable repeatability as compared to other regulated emissions. (3) In particle number concentration emitted from different-fueled vehicles, the sources of particle emissions in an ascending order of magnitude are as follows: DPF equipped diesel passenger vehicles, gasoline and LPG fueled vehicles, and DPF unequipped diesel passenger vehicles. Also, we found that the particle numbers of DPF equipped diesel passenger vehicles, gasoline and LPG-fueled vehicles can meet the EU regulation limit (< $6.0{ imes}10^{11}$#/km), while DPF unequipped diesel passenger vehicles do not meet the EU limit.