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Emission Test Cycles


Time-speed data points: ECE | EUDC | EUDC (low power)

ECE+EUDC. The ECE+EUDC test cycle—also known as the MVEG-A cycle—was used for EU type approval testing of emissions and fuel consumption from light duty vehicles [EEC Directive 90/C81/01]. The test is performed on a chassis dynamometer. The entire cycle includes four ECE segments (Figure 1) repeated without interruption, followed by one EUDC segment (Figure 2). Before the test, the vehicle is allowed to soak for at least 6 hours at a test temperature of 20-30°C. It is then started and allowed to idle for 40s.

NEDC. Effective year 2000, that idling period has been eliminated, i.e., engine starts at 0 s and the emission sampling begins at the same time. This modified cold-start procedure is referred to as the New European Driving Cycle (NEDC) or as the MVEG-B test cycle.

The full test starts with four repetitions of the ECE cycle (Figure 1). The ECE is an urban driving cycle, also known as UDC. It was devised to represent city driving conditions, e.g. in Paris or Rome. It is characterized by low vehicle speed, low engine load, and low exhaust gas temperature.

Figure 1. ECE 15 Cycle

The EUDC (Extra Urban Driving Cycle) segment has been added after the fourth ECE cycle to account for more aggressive, high speed driving modes. The maximum speed of the EUDC cycle is 120 km/h. An alternative EUDC cycle for low-powered vehicles has also been defined with a maximum speed limited to 90 km/h, Figure 3.

Figure 2. EUDC Cycle
Figure 3. EUDC Cycle for Low Power Vehicles

Emissions are sampled during the cycle according to the constant volume sampling (CVS) technique, analyzed, and expressed in g/km for each of the pollutants.

The following table includes a summary of selected parameters for the ECE 15, EUDC and NEDC cycles.

CharacteristicsUnitECE 15EUDCNEDC†
Total times1954001180
Idle (standing) times5739267
Average speed (incl. stops)km/h18.3562.5933.35
Average driving speed (excl. stops)km/h25.9369.3643.10
Maximum speedkm/h50120120
Average acceleration1m/s20.5990.3540.506
Maximum acceleration1m/s21.0420.8331.042
† Four repetitions of ECE 15 followed by one EUDC
1 Calculated using central difference method

Type I, II and III Tests. The urban driving cycle—ECE 15, Figure 1—represents Type I test, as defined by the original ECE 15 emissions procedure. Type II test is a warmed-up idle tailpipe CO test conducted immediately after the fourth cycle of the Type I test. Type III test is a two-mode (idle and 50 km/h) chassis dynamometer procedure for crankcase emission determination.