State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, China.
Tsinghua Automotive Strategy Research Institute, Tsinghua University, Beijing 100084, China.
Int J Environ Res Public Health. 2021 Mar 19;18(6):3199. doi: 10.3390/ijerph18063199.
As a main measure to promote the development of China's energy-saving and new energy vehicles, the Phase V fuel consumption regulation is dramatically different from the past four phases, especially in the test procedure, moving from the New European Driving Cycle (NEDC) to the worldwide harmonized light duty test cycle (WLTC) and corresponding test procedure (WLTP). The switch of test procedure will not only affect the effectiveness of technologies but also change the fuel consumption target of the industry. However, few studies have systematically investigated the impacts of the new WLTP on the Chinese market. This study establishes a "technology-vehicle-fleet" bottom-up framework to estimate the impacts of test procedure switching on technology effectiveness and regulation stringency. The results show that due to the WLTP being closer to the real driving condition and more stringent, almost all baseline vehicles in the WLTP have higher fuel consumption than that in the NEDC, and diesel vehicles are slightly more impacted than gasoline vehicles. In addition, the impacts are increased with the strengthening of electrification, where the fuel consumption of plug-in hybrid electric vehicles (PHEVs) and range-extended electric vehicles (REEVs) in the WLTP are about 6% higher than that in the NEDC. Engine technologies that gain higher effects in low load conditions, such as turbocharging and downsizing, fuel stratified injection (FSI), lean-burn, and variable valve timing (VVT), are faced with deterioration in the WLTP. Among these, the effect of turbocharging and downsizing shows a maximum decline of 8.5%. The variable compression ratio (VCR) and stoichiometric gasoline direct injection (SGDI) are among the few technologies that benefited from procedure switching, with an average improvement of 1.6% and 0.2% respectively. Except for multi-speed transmissions, which have improvement effects in the WLTP, all automatic transmissions are faced with decreases. From the perspective of the whole fleet and national regulation target, the average fuel consumption in the WLTP will increase by about 7.5% in 2025 compared to 4 L/100 km in the NEDC. According to the current planning of the Chinese government, the fuel consumption target of Phase V is set at 4.6 L/100 km in 2025, which is equivalent to loosening the stringency by 0.3 L/100 km. In Phase VI, the target of 3.2 L/100 km is maintained, which is 30.4% stricter than that of Phase V, and the annual compound tightening rate reaches 7.5%. This means that automakers need to launch their product planning as soon as possible and expand the technology bandwidth to comply with the Phase VI fuel consumption regulation, and the government should evaluate the technical feasibility before determining the evaluation methods and targets of the next phase.
作为推动中国节能与新能源汽车发展的主要措施，第五阶段燃料消耗法规与过去四个阶段有很大的不同，尤其是在测试程序方面，从新欧洲驾驶循环（NEDC）转变为全球轻型车测试循环（WLTC）和相应的测试程序（WLTP）。测试程序的切换不仅会影响技术的有效性，还会改变行业的燃料消耗目标。然而，很少有研究系统地研究新的 WLTP 对中国市场的影响。本研究建立了一个“技术-车辆-车队”的自下而上框架，以估计测试程序切换对技术效果和法规严格程度的影响。结果表明，由于 WLTP 更接近实际驾驶条件，且更为严格，WLTP 中的几乎所有基线车辆的燃料消耗都高于 NEDC，柴油车受影响略高于汽油车。此外，随着电气化程度的提高，插电式混合动力汽车（PHEV）和增程电动汽车（REEV）在 WLTP 中的燃料消耗比 NEDC 高出约 6%。在低负荷条件下获得更高效果的发动机技术，如涡轮增压和缩小排量、燃油分层喷射（FSI）、稀燃和可变气门正时（VVT），在 WLTP 中面临恶化。其中，涡轮增压和缩小排量的效果下降最大，可达 8.5%。可变压缩比（VCR）和均质汽油直接喷射（SGDI）是少数受益于程序切换的技术之一，平均提高 1.6%和 0.2%。除了多速变速器在 WLTP 中有改进效果外，所有自动变速器都面临下降。从整个车队和国家法规目标的角度来看，2025 年 WLTP 中的平均燃料消耗将比 NEDC 中的 4L/100km 增加约 7.5%。根据中国政府目前的规划，第五阶段的燃料消耗目标设定为 2025 年 4.6L/100km，相当于放宽 0.3L/100km。在第六阶段，维持 3.2L/100km 的目标，比第五阶段严格 30.4%，年复合收紧率达到 7.5%。这意味着汽车制造商需要尽快启动产品规划，并扩大技术带宽，以符合第六阶段的燃料消耗法规，政府在确定下一阶段的评估方法和目标之前，应评估技术可行性。
