Knowledge

Against the backdrop of decarbonization efforts aimed at reducing the burden on the global environment and achieving a sustainable society, initiatives to improve vehicle fuel efficiency are progressing. Especially over the past decade, public interest has grown due to the adoption of the Sustainable Development Goals (SDGs), unanimously endorsed by participating countries at the UN Summit in September 2015. The SDGs comprise 17 goals. Goal 13, on climate action, states: "Take urgent action to combat climate change and its impacts."

Recently in Japan, severe damage has occurred due to the generation of large and powerful typhoons, believed to be caused by rising sea temperatures due to global warming, and the frequent occurrence of linear rainbands that cause heavy rainfall, resulting from increased atmospheric instability conducive to the continuous development of cumulonimbus clouds. To ensure people's safe and secure lives, it's essential to curb such environmental deterioration, and this necessity feels palpable today.

Figure 1 shows the trend of the average fuel efficiency (JC08 mode) for gasoline passenger vehicles, as published by the Ministry of Land, Infrastructure, Transport and Tourism for fiscal year 2024. Each line in the figure represents the change in fuel efficiency by vehicle weight from 2011 to 2022. From the figure, it's clear that lighter vehicles have better fuel efficiency.

This indicates that vehicle weight reduction improves fuel efficiency, which in turn decreases gasoline consumption and suppresses CO2 emissions, contributing to the mitigation of global warming. Furthermore, observing the trend in fuel efficiency across different vehicle weights, there's a general tendency for fuel efficiency to improve. While this is partly due to enhanced engine combustion efficiency and reduced frictional resistance in moving parts, the application of lightweight and high-strength materials is considered to be a significant contributor to this improvement in fuel efficiency.