Abstract
The paper presents results of the road tests of exhaust gas emissions of vehicles of different emission classes (Euro 4 and Euro 5, with different mileage), fuelled with compressed natural gas. The tests of exhaust emissions were conducted on parts of the road with different characteristics of the traffic intensity. For each phase of the tests, the characteristics of the test run and the value of exhaust gas emissions were determined. To measure the concentration of harmful substances, the Portable Emission Measurement System (PEMS) was used. The results were used to compare the vehicles and determine the emission indices, which subsequently were used to assess from ecological point of view the objects of tests in terms of emissions of toxic substances.
KEYWORDS – compressed natural gas, exhaust emission, real traffic conditions