**Abbreviations**

**Figure 22.** Comparison of the on-road emission of CO, NOx

122 Improvement Trends for Internal Combustion Engines

in the gas mileage (by 2.9 dm3

global outreach.

particularly in terms of NOx

to the Euro III standard is 60% and over 90%, respectively.

, CO2

The reduction of exhaust emissions requires a continuous search for new solutions in terms of both the design of engines/powertrains and the methodology of their testing. A factor stimulating this advancement is the exhaust emissions legislation. The advancement of the exhaust emissions measurement technology has created new possibilities in terms of measurements performed under actual conditions of operation. Supposedly, this particular method will be further developed and will gain in importance. A natural reaction of the legislators and manufacturers should be the recognition of measurements under actual operation as one of the main methods of homologation testing. Relevant works aiming at the introduction of such changes should finish without delay and the resultant legislation should be of

The PEMS-based measurements have provided invaluable information regarding the emissions under actual operation of vehicles including their operating parameters. One of the most important observations is the difference in the emissions between the homologation tests and the tests performed under actual operation. The results of the measurements performed on LDV vehicles indicate significant differences, particularly in terms of NO<sup>x</sup>

HC. The reasons for that are different parameters in the homologation tests and those under actual operation. The differences for the HDV Euro III and Euro V compliant vehicles are big,

referring these results to the Euro III (vehicle A) and Euro V (vehicle B) limits, the differences are smaller—the reduction of the emission of NOx and PM in the Euro V standard compared

of long-haulage trucks. The greatest drop was observed for the on-road emission of NOx

mainly resulted from the application of the SCR system in vehicle B.

, PM and gas mileage of the tested vehicles.

, which

and

/100 km). The cost of fuel is currently the main cost of operation

and PM. They amount to 45 and 10%, respectively. However,


