Many current approaches to emissions reductions can come at the expense of fuel consumption. Meeting both goals for entire classes of vehicles will require some tremendous engineering creativity: alternative fuels, new combustion processes, greatly improved mechanisms for waste heat recovery and hybrid configurations could all play roles.

The standards, which would be introduced this coming April, are aimed at improving fuel consumption of these vehicles by about 12% on average from their fiscal 2002 levels by fiscal 2015.

Targets for improving fuel consumption will be set for 11 weight categories of trucks weighing more than 3.5 tons. A target for 2.5- to 3.5-ton vehicles will be set at a later date. The standards would improve the fuel economy of trucks over 3.5 tons by an average of 12.2% by fiscal 2015. For buses, fuel economy would improve by an average of 12.1%.

Manufacturers failing to meet the targets will receive corrective action orders from the ministries. If they still fail to meet the standards, they and the models will be publicly named and fines levied. Pressure would be applied to end production of poorly performing models.

The regulations are designed to help Japan meet its Kyoto targets for reducing CO₂ emissions. The country has seen a 20% increase in CO₂ emissions in the transportation sector since 1990—heading in the wrong direction, in other words. By contrast, emissions from the industrial sector have been flat, despite growth in the economy.