The article presents the results of emission tests and vehicle operation indicators fueled with diesel oil. The tests were carried out for a passenger vehicle equipped with a diesel engine meeting Euro 3 emissions standard, moving in urban traffic. The measurements were carried out using modern PEMS (Portable Emission Measurement System) enabling the emission of gaseous components from exhaust systems of the tested object. On the basis of the conducted tests, the load characteristics were determined using the torque values obtained along with the engine speeds. The measurement route included two cycles: urban driving and fast acceleration. The aim of the study was to assess the impact of modifications to the control maps on CO, CO2, PM and NOx exhaust gas emissions under real operating conditions.