The paper gives an overview of possibilities to determine the values of tractor's fuel consumption, exhaust emissions and engine load in real operating conditions by using data accumulated in electronic control units. There is ecological and economic importance for the tractors to be operated correctly: time of engine idling, operation at low and too high loads or high speeds should be shortened. To monitor tractor's operating performance, tools and techniques are necessary that would allow to determine the controlled indicators. The paper presents research of tractor's engine load factor, fuel consumption and engine exhaust emissions during operation of ploughing. The research is conducted on the base of data accumulated in engine's electronic control units. Histograms are presented that show time intervals of the ploughing process, fuel consumption and emission components (CO2, NOx and CO) in engine speed and cyclic fuel injection modes. Test results are analyzed separately for the processes of technological ploughing and works at headlands. Test results showed that in the ploughing process, the main amount of fuel was consumed and CO2 emitted during technological process of ploughing, and CO - during the work at headlands. Large quantities of NOx were emitted during technological process of ploughing, and during the work at headlands as well. (C) 2013 Published by Elsevier Ltd.