# Reduce CO₂ Emissions from Automobiles—Conversion towards Fuel-Efficient Vehicles and Public Transportation

The transport sector accounts for about 20% of $ CO_{2} $ emissions resulting from energy use, with vehicles accounting for about 90% of these emissions, of which about 60% are private vehicles (hereinafter referred to as automobiles). That means automobiles emit about half of the $ CO_{2} $ emissions of the transport sector. Looking back several years, upsizing of automobiles and increase in the number of units has continued to grow in the 1990s, and in increased $ CO_{2} $ emissions of the entire transport sector, due to decreased per kilometer fuel consumption. In the 2000s, $ CO_{2} $ emissions have peaked, since the number of fuel-efficient vehicles and per kilometer fuel consumption have increased.

Relationships between $ CO_{2} $ Emissions Resulting from Private Vehicles and Passenger Transportation Volume

Source : Compiled by the Ministry of the Environment from the data of the Ministry of Transport's "Handbook on Transportation-Related Energy Consumption" and the Ministry of Land, Infrastructure, Transport and Tourism's "The Survey on Transport Energy"

Various factors, as listed in the above chart, are the likely cause of this. For example, the automobile tax reduction (1989) has become a factor to increase the number of mid-size cars (the so-called three numbers plates). The strengthening of green taxation (implemented at a full-scale from 2001) has also become a factor to progress the dissemination of fuel-efficient vehicles and the taxation system is considered to be related as this factor.

CO $ _{2} $ emissions resulting from automobile use have shown an increasing trend until about a decade ago, but since the passenger

Relationships between $ CO_{2} $ Emissions Resulting from Private Vehicles and Passenger Transportation Volume

Source: Compiled by the Ministry of the Environment from the Energy Data and Modelling Center (EDMC), the Institute of Energy Economics, Japan's Transportation Sector's Volume of Transportation by Mode from the "GHGs Inventory"

transportation volume leveled off in the 2000s, the emissions have shown a decreasing trend. In order to keep reducing emissions, improvement of transportation efficiency and promotion of modal shift (conversion of transportation means) are necessary, in addition to improvement of per kilometer fuel consumption, low carbonization of fuels and the reduction of automobile mileage. Promotion of decoupling—to increase convenience and productivity, while reducing $ CO_{2} $ emissions—are also required to curb passenger transportation volume itself by utilizing intensive land use and IT.

Conversion towards fuel-efficient vehicles and public transportation is a way to reduce $ CO_{2} $ emissions from automobiles.

First, we will look at the effect of reducing $ CO_{2} $ emissions of automobiles used for short journeys, such as local commuting and shopping. According to the “Research on reduction of environmental load by a review of daily use transportation,” conducted by the National Institute for Environmental Studies (NIES), on-road tests on next generation electric vehicles showed that about a 60% to 70% reduction in $ CO_{2} $ emissions can be expected by switching automobiles from gasoline minivans (4AT) to electric vehicles (seating capacity of 2). On the other hand about 50% to 60% reduction of $ CO_{2} $ emissions can be expected by switching automobiles from gasoline minivans (CVT) to electric vehicles (seating capacity of 2).