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. 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).

Two important sets of fuel efficiency targets are the 2010 targets and the 2015 targets (the latter also known as new fuel efficiency targets). These requirements were adopted through a number of amendments to the Energy Conservation Law, as follows:

  • 1999—Adoption of 2010 fuel efficiency targets for gasoline passenger cars and light commercial 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 for light vehicles, including revisions to passenger car and light commercial vehicles standards, and new standards for small buses.

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 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.

Table 1.1
2010 Fuel Efficiency Targets for Passenger Cars
Vehicle Weight, kgFuel Economy Target, km/L
GasolineDiesel*LPG
< 70321.218.915.9
703-82718.8 14.1
828-101517.9 13.5
1016-126516.016.212.0
1266-151513.013.29.8
1516-176510.511.97.9
1766-20158.910.86.7
2016-22657.89.85.9
> 22656.48.74.8
* Diesel vehicle targets effective from 2005

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.

Table 1.2
2010 Fuel Efficiency Targets for Gasoline Light Commercial Vehicles
TypeTransmissionGVW, kgStructureFE Target, km/L
Mini Cargo VehiclesMT< 703A20.2
B17.0
703-828A18.0
B16.7
> 82815.5
AT< 703A18.9
B16.2
703-827A16.5
B15.5
> 82814.9
Small Cargo Vehicles
GVW ≤ 1.7 t
MT< 101617.8
≥ 101615.7
AT< 101614.9
≥ 101613.8
Medium Cargo Vehicles
1.7 t < GVW ≤ 2.5 t
MT< 1266A14.5
B12.3
1266-151510.7
≥ 15169.3
AT< 1266A12.5
B11.2
≥ 126610.3
Table 1.3
2010 Fuel Efficiency Targets for Diesel Light Commercial Vehicles
TypeTransmissionGVW, kgStructureFE Target, km/L
Small Cargo Vehicles
GVW ≤ 1.7 t
MT17.7
AT15.1
Medium Cargo Vehicles
1.7 t < GVW ≤ 2.5 t
MT< 1266A17.4
B14.6
1266-151514.1
≥ 151612.5
AT< 1266A14.5
B12.6
1266-151512.3
1516-176510.8
≥ 176610.3

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

Light-Duty 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 busses: 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).

Table 2.1
2015 Fuel Efficiency Targets for Passenger Cars
CategoryVehicle Weight, kgFE Target, km/L
1≤ 60022.5
2601-74021.8
3741-85521.0
4865-97020.8
5971-108020.5
61081-119518.7
71196-131017.2
81311-142015.8
91421-153014.4
101531-165013.2
111651-176012.2
121761-187011.1
131871-199010.2
141991-21009.4
152101-22708.7
16≥ 22717.4

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.

Table 2.2
2015 Fuel Efficiency Targets for Small Buses
CategoryFuel TypeFE Target, km/L
1Gasoline8.5
2Diesel9.7

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.

Table 2.3
2015 Fuel Efficiency Targets for Mini Cargo Vehicles
CategoryStructureTransmissionVehicle Weight, kgFE Target, km/L
1AMT≤ 74023.2
2≥ 74120.3
3AT≤ 74020.9
4741-85519.6
5≥ 85620.5
6BMT≤ 74018.2
7741-85518.0
8856-97017.2
9≥ 97116.4
10AT≤ 74016.4
11741-85516.0
12856-97015.4
13≥ 97114.7
Table 2.4
2015 Fuel Efficiency Targets for Light Cargo Vehicles, GVW ≤ 1.7 t
CategoryTransmissionVehicle Weight, kgFE Target, km/L
1MT≤ 108018.5
2≥ 108117.1
3AT≤ 108017.4
41081-119515.8
5≥ 119614.7
Table 2.5a
2015 Fuel Efficiency Targets for Gasoline Medium Cargo Vehicles
(1.7 t < GVW ≤ 3.5 t)
CategoryStructureTransmissionVehicle Weight, kgFE Target, km/L
1AMT-14.2
2AT≤ 131013.3
3≥ 131112.7
4B1MT≤ 131011.9
51311-142010.6
61421-153010.3
71531-165010.0
81651-17609.8
9≥ 17619.7
10AT≤ 131010.9
111311-14209.8
121421-15309.6
131531-16509.4
141651-17609.1
151761-18708.8
16≥ 18718.5
17B2MT≤ 131011.2
181311-142010.2
191421-15309.9
201531-16509.7
211651-17609.3
22≥ 17618.9
23AT≤ 131010.5
241311-14209.7
251421-15308.9
261531-16508.6
27≥ 16517.9
Table 2.5b
2015 Fuel Efficiency Targets for Diesel Medium Cargo Vehicles
(1.7 t < GVW ≤ 3.5 t)
CategoryStructureTransmissionVehicle Weight, kgFE Target, km/L
28A & B1MT≤ 142014.5
291421-153014.1
301531-165013.8
311651-176013.6
321761-187013.3
331871-199012.8
341991-210012.3
35≥ 210111.7
36AT≤ 142013.1
371421-153012.8
381531-165011.5
391651-176011.3
401761-187011.0
411871-199010.8
421991-210010.3
43≥ 21019.4
44B2MT≤ 142014.3
451421-153012.9
461531-165012.6
471651-176012.4
481761-187012.0
491871-199011.3
501991-210011.2
51≥ 210111.1
52AT≤ 142012.5
531421-153011.8
541531-165010.9
551651-176010.6
561761-18709.7
571871-19909.5
581991-21009.0
59≥ 21018.8

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).

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.

Table 3.1
2015 Fuel Efficiency Targets for Heavy-Duty Transit Buses
CategoryGVW, tFE Target, km/L
16 < GVW ≤ 86.97
28 < GVW ≤ 106.30
310 < GVW ≤ 125.77
412 < GVW ≤ 145.14
514 < GVW4.23
Table 3.2
2015 Fuel Efficiency Targets for Heavy-Duty General (Non-Transit) Buses
CategoryGVW, tFE Target, km/L
13.5 < GVW ≤ 69.04
26 < GVW ≤ 86.52
38 < GVW ≤ 106.37
410 < GVW ≤ 125.70
512 < GVW ≤ 145.21
614 < GVW ≤ 164.06
716 < GVW3.57
Table 3.3
2015 Fuel Efficiency Targets for Heavy-Duty Trucks (Excluding Tractors)
CategoryGVW, tMax Load (L), tFE Target, km/L
13.5 < GVW ≤ 7.5L ≤ 1.510.83
21.5 < L ≤ 210.35
32 < L ≤ 39.51
43 < L8.12
57.5 < GVW ≤ 87.24
68 < GVW ≤ 106.52
710 < GVW ≤ 126.00
812 < GVW ≤ 145.69
914 < GVW ≤ 164.97
1016 < GVW ≤ 204.15
1120 < GVW4.04
Table 3.4
2015 Fuel Efficiency Targets for Heavy-Duty Tractors
CategoryGVW, tFE Target, km/L
1GVW ≤ 203.09
2GVW > 202.01

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.