**6. Conclusions**

Energy intensity is one of the important factors that influence CO2 emissions [36,37]. In this respect, this study introduced the current status of South Korea's passenger cars from two perspectives. First, the shift in consumer preferences towards large-sized cars is deteriorating the overall energy intensity of passenger cars. Second, the increasing promotion of BEVs could improve the energy intensity of passenger cars. CAFE standards were implemented for improving the energy intensity of passenger cars in South Korea. This study assessed CAFE standards by doing a sensitivity analysis of energy intensity improvement scenarios using GCAM. In addition to an analysis of the scenarios the study also assessed the credit system of CAFE standards.

The results are summarized as follows. First, all scenarios have a negligible impact on total service demand by passenger cars and on the overall trends of market share among ICEVs, BEVs, and FCEVs. According to the CAFE performance analysis, all scenarios will achieve CAFE standards in 2030 if the current credit system of three credits for one BEV or FCEV sale or at least two credits for one BEV or

FCEV sale is kept. However, in the case of no additional credits for one BEV or FCEV sale (that is, one credit for a BEV or an FCEV sale), the reference and the Mod-EI scenario will not achieve CAFE standards in 2030.

Some other findings of this study are as follows: First, from the policy design perspective, a proper setting of the credit system for BEVs and FCEVs will be a very important variable for automakers to achieve CAFE standards. Second, from the technology promotion perspective, active promotion of fuel efficiency improvements through CAFE standards is important since the Mod-EI scenario does not achieve CAFE standards when the credit for a BEV is one car sale in 2030.

The current study can be extended to include the following issues: First, various types of hybrid electric vehicles can be explicitly considered by extending this study. Second, various types of costs not included in vehicle costs, such as user costs, inconvenience costs, and time costs of refueling, can be modeled by applying this study if additional information becomes available.
