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From the perspective of improving the atmospheric environment, evaluating the fuel efficiency and exhaust gas emissions when using actual vehicles on real roads is necessary. Passenger vehicles apply RDE (real driving emission) test. However, unlike passenger vehicles, there are many types and models of heavy-duty vehicles; thus, evaluating all of these types using real driving emission tests is difficult. Therefore, we investigated the possibility of an alternative evaluation of heavy-duty vehicle based on a simulation method that uses a vehicle model for part of the evaluation. This alternative evaluation method is a combination of the “engine HILS (hardware-in-the-loop simulation)” method, developed in previous studies and can perform tests based on vehicle speed and driving wind that is reproduced in the engine bench to appropriately cool the engine and various devices.

Electric vehicles have become more widespread globally, with the aim of realizing a carbon-neutral society. In addition, the various policies for vehicle engines have become increasingly strict. It is desirable to evaluate fuel consumption and exhaust emissions using real vehicles on actual roads, with the goal of improving air quality. Hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) have a high frequency of engine stops during driving. In a real driving emission (RDE) test, a portable emission measurement system (PEMS) is used, which continues to measure emissions even when the engine stops; this can decrease the emission concentration inside the tailpipe and result in an inaccurate emission measurement. Furthermore, RDE tests are affected by the installation performance of the PEMS; the emission intake is often installed by extending the exhaust outlet.