Electric and lightweight vehicles can help reduce CO2 emissions in passenger transportation. A study in Japan looked at how switching to electric or smaller, lighter vehicles can impact energy use, emissions, and cost. Mini-sized lightweight electric cars could cut energy consumption and emissions by over 70% by 2050, with positive cash flow until 2045. On the other hand, mini-sized lightweight fuel cell cars may have lower cash flow and reduce emissions by around 80%. Using lighter materials can also lower the cost of electric and fuel cell cars, making them more affordable.