Japan: Fuel Economy

Background

Japanese vehicle fuel economy regulations are part of the “Law Concerning the Rational Use of Energy” (Energy Conservation Law). The Law, adopted in 1976 and amended on a number of occasions, covers energy efficiency requirements for a wide variety of products. The first vehicle fuel efficiency standards, adopted in the 1979 amendments, were applicable to new gasoline cars from 1985.

Since 1998, energy efficiency standards under the Energy Conservation Law are developed using a ‘top runner’ approach [4532]. In the ‘top runner’ method, future targets are based on the most energy efficient product that is available on the market. Other factors are also considered, both positive (progress in technology) and negative (e.g., trade-off with more stringent emissions).

Vehicle fuel efficiency targets are strengthened from time to time through amendments to the Energy Conservation Law. Some of the important amendments include:

• 1999—Adoption of 2010 fuel efficiency targets for gasoline passenger cars and light commercial (freight) vehicles (effective 2005 for diesel vehicles).
• 2003—Fuel efficiency standards for LPG cars (2010 targets).
• 2006—New fuel efficiency standards for heavy vehicles above 3.5 t (2015 targets).
• 2007—Adoption of 2015 fuel efficiency targets (also known as new fuel efficiency targets) for passenger cars and light commercial (freight) vehicles, and new standards for small buses.
• 2011—Adoption of 2020 fuel efficiency targets for light-duty passenger vehicles.
• 2019—Adoption of 2030 fuel efficiency standards for light-duty passenger vehicles.

The fuel efficiency targets, expressed in kilometers per liter of fuel (km/L), are based on the gross vehicle weight (GVW) category. Manufactures must ensure that in each financial year the average fuel economy of their vehicles in each weight category meets the standard. Flexibilities exist that allow manufacturers to accumulate credits in one weight category for use in another. While the fuel economy targets are mandatory, the penalties for missing the targets are minimal.

The effectiveness of the standards is enhanced by financial incentives—such as progressive taxes levied on the vehicle weight and engine displacement—that promote the purchase of lighter vehicles. Vehicles that exceed the fuel economy standards and emission standards may be also eligible for additional reductions in vehicle tax. A sticker system is in place that allows customers to identify vehicles that exceed standards.

Light-Duty Passenger & Freight Vehicles: 2010 Targets

The fuel economy targets apply to new type-approved passenger cars and light trucks with GVW ≤ 2.5 t. Standards for gasoline and LPG vehicles become effective from 2010, while the standards for diesel vehicles are applicable from 2005. According to government estimates, when the targets are met the average fuel economy for the entire vehicle fleet would reach:

• Passenger cars: 15.1 km/L (153.8 g CO₂/km), a 22.8% increase over 1995 performance of 12.3 km/L (188.8 g CO₂/km),
• Light trucks (2.5 t): 16.3 km/L (124.4 g CO₂/km), a 13.2% increase over 1995 performance of 14.4 km/L (161.2 g CO₂/km).

Passenger Cars. The standards for gasoline, diesel and LPG passenger cars (≤ 10 passengers) are shown in Table 1.1.

Light Commercial Vehicles. The standards for light vehicles (GVW ≤ 2.5 t) used to transport cargo are listed in Table 1.2 and Table 1.3 for gasoline and diesel vehicles, respectively. The standards depend on the type of transmission (MT - manual; AT - automatic) and vehicle structure. The vehicle structures refer to cab-behind-engine (bonnet type) trucks and vans for Structure A, and cab-over-engine for Structure B.

Testing. Fuel consumption is measured over the hot start 10-15 mode cycle.

Light-Duty Passenger & Freight Vehicles: 2015 Targets

The 2015 fuel efficiency regulation introduces more GVW categories and applies to more vehicle types. New standards are introduced for small buses, and the applicability of standards for light trucks (cargo vehicles) is extended up to GVW ≤ 3.5 t. Therefore, the 2015 targets apply to most type-approved vehicles below 3.5 t (with the exception of LPG vehicles other than passenger cars, and all vehicles fueled by other fuels than gasoline, diesel, or LPG).

When the 2015 targets are met, the fleet average fuel economy is estimated to be:

• Passenger cars: 16.8 km/L, a 23.5% increase over 2004 performance of 13.6 km/L,
• Light trucks (3.5 t): 15.2 km/L, a 12.6% increase over 2004 performance of 13.5 km/L.
• Small buses: 8.9 km/L, a 7.2% increase over 2004 performance of 8.3 km/L.

Passenger Cars. The fuel economy standards for passenger cars (≤ 10 passengers) are listed in Table 2.1. The same standards apply to gasoline and diesel cars, but a heating value correction applies for diesels (see “testing” below).

Small Buses. Fuel economy standards for small buses, defined as vehicles designed to carry 11 or more passengers and with GVW up to 3.5 t, are shown in Table 2.2.

Light Commercial Vehicles. Fuel economy targets for light vehicles with GVW up to 3.5 t used to transport cargo are summarized in the following tables. The standards depend on the type of transmission (MT - manual; AT - automatic) and vehicle structure. The vehicle structures refer to cab-behind-engine (bonnet type) vans for Structure A, cab-over-engine vans for Structure B1, and cab-over-engine trucks for Structure B2. Structure B refers to vehicles of Structure B1 and B2 combined.

Testing. The 2015 fuel consumption testing is performed over the JC08 cycle, which fully replaces the 10-15 mode test by 2011. A weighted harmonic average (i.e., the reciprocal of the weighted average of reciprocals of the measured data) is calculated from the cold start (weight = 0.25) and hot start (0.75) runs. The higher average speed, quicker acceleration, and the cold start requirements of the JC08 test increase the stringency of the new fuel economy targets by about 9%. The fleet average passenger car fuel economy for 2004 vehicles is 15.0 km/L when measured over the 10-15 test, compared to 13.6 km/L over the JC08 test.

For passenger vehicles (Table 2.1), mini cargo vehicles (Table 2.3), and light cargo vehicles (Table 2.4), gasoline and diesel vehicles are placed in the same category with equal target standards. In these cases, a weighted harmonic average should be obtained using fuel efficiency values for gasoline vehicles and gasoline-heating-value-equivalent fuel efficiency values for diesel vehicles (fuel efficiency of diesel vehicles divided by 1.10).

Light-Duty Passenger Vehicles: 2020 Targets

When the 2020 targets are met, the fleet average fuel economy for passenger cars is estimated to be 20.3 km/L, a 19.6% increase over 2015 performance of 17.0 km/L. The target values are listed in Table 3.

The standards are applicable to light-duty passenger vehicles (a capacity of 10 passengers or less, GVW of 3.5 tonnes or less) fueled by gasoline, diesel or LPG. Fuel efficiency is determined over the JC08 test cycle. The values in Table 3.1 are directly applicable to gasoline vehicles. A fuel heating value correction of 1.10 is applied to diesel vehicles, and of 0.78 for LPG vehicles.

Light-Duty Passenger Vehicles: 2030 Targets

The 2030 standards, adopted in June 2019, follow the same top-runner concept as the previous standards. The standards require an average fleet gasoline-equivalent fuel economy of 25.4 km/L by 2030, which is a 32.4% improvement over the 2016 fleet average.

The 2030 standards include several important changes, not only in stringency, but also in the structure of the regulation [4533]:

• Bin-based targets are replaced with a linear curve—In the 2020 and earlier standards, fuel economy targets are set for different vehicle weight bins. The 2030 standards define fuel efficiency targets with respect to vehicle weight as a continuous curve with a minimum fuel economy floor for the heaviest vehicles, Figure 1.

• The test cycle has changed —The 2020 targets were set on the JC08 test cycle, while the 2030 standards are tested over the WLTP. The extra-high-speed phase is excluded from the WLTP to reflect slower driving on Japan’s more congested roads.
• The scope is expanded to electric vehicles (EV)—The 2030 standards are expanded to cover battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs), in addition to gasoline, diesel and LPG vehicles.
• Comparative upstream energy efficiency is considered—The earlier standards only take account of tank-to-wheel (TTW) fuel consumption. Since EVs are included for the first time, the 2030 standards are well-to-wheel (WTW) and take account of the domestic upstream energy consumption of all fuel sources.

Heavy-Duty Vehicles: 2015 Targets

The fuel economy standards for heavy vehicles—effective from 2015—apply to diesel fueled, type-approved commercial vehicles with GVW > 3.5 t, including trucks and buses designed to carry 11 or more passengers. The standards are also applicable to non-type-approved diesel vehicles that are equipped with CO or other emission control devices. Fuel economy from heavy vehicles fueled by gasoline, LPG or other alternative fuels is not regulated.

When the targets are fully met, the fleet average fuel economy is estimated at:

• For trucks: 7.09 km/L (369.6 g CO₂/km), a 12.2% increase over 2002 performance of 6.32 km/L (414.6 g CO₂/km),
• For buses: 6.30 km/L (416.0 g CO₂/km), a 12.1% increase over 2002 performance of 5.62 km/L (466.3 g CO₂/km).

The standards for heavy vehicles are summarized in the following tables.

Testing. A computer simulation procedure has been developed that allows to calculate fuel efficiency (in km/L) of heavy-duty trucks and buses based on engine dynamometer testing. The engine testing is performed over the urban JE05 test and over an interurban transient test (speed: 80 km/h, load factor: 50%). A number of vehicle factors, such as vehicle mass, payload, tire size, gear ratios and efficiency, and others are accounted for in the calculation.