The paper presents a comparative analysis of the emission of CO, NOx, CO2 and gas mileage for two heavy-duty long haulage vehicles. The tests were performed on the same test road. The test route reflected typical daily operation of heavy-duty vehicles – a drive to the loading/unloading zone and cruise on national roads. In the investigations, the authors used a portable exhaust emissions analyzer (SEMTECH DS, PEMS – Portable Emissions Measurement System). Based on the performed analysis, optimum engine was selected for long haulage vehicles under conditions of Polish transport and logistic infrastructure in terms of fuel consumption.