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May 2012 

Interim Test Method for Verifying 

Fuel-Saving Components for SmartWay: 

Modifications to SAE J1321 

SmartWay 

Tractor & Trailer 

Program 

U.S. Environmental Protection 

Agency Designated SmartWay 

tractors and trailers are a new 

generation of long-haul rigs 

equipped with cleaner, fuel-saving 

features. SmartWay tractors and 

trailers can achieve fuel savings 

of 10 to 20 percent (saving car 

riers between 1,700 and 3,300 

gallons of diesel fuel annually), 

lower greenhouse-gas emissions, 

and significantly reduce oxides of 

nitrogen, particulate matter, and 

other air pollutants. 

This is an EPA document listing 

the U.S. Environmental Protection 

Agency how the Joint TMC/SAE 

Fuel Consumption Test Procedure 

– Type II SAE J1321 Surface Vehicle 

Recommended Practice (October, 

1986) to create an interim test meth 

od to quantify the fuel consumption 

impact of fuel-saving equipment. 

This test method is intended for 

testing new class 8, sleeper cabs 

and certain trailer aerodynamic 

components for the purpose of 

determining eligibility for inclusion 

in SmartWay. 

Modification to Joint SAE/TMC 

The Joint TMC/SAE Fuel Consumption Test Procedure – Type II (SAE J1321 

Surface Vehicle Recommended Practice (October, 1986) is modified by adding the following provisions: 

1.	 Test must be conducted on a test track, not a roadway. 

2.	 Test track length greater than 1.5 miles (5 miles recommended). 

3.	 Track must be circular, figure eight, or oval in shape. 

4.	 Track surface must be completely dry, well-maintained, and be comprised of a surface typical of highway surfaces (asphalt or cement). 

5.	 Grade change on test track not greater than 2 degrees. 

6.	 Altitude of test facility not greater than 4,000 feet above sea level. 

7.	 No precipitation on the test track for duration of test. 

8.	 Ambient air temperatures at the test track must be between 5 C to 35 

C (41 F to 95 F) provided that the air temperature during the entire test 

does not fluctuate more than 30 degrees F (approximately 16.6 C). 

9.	 Wind speed at the test track cannot exceed 12 mph for duration of test. 

10.	 Wind gusts at the test track cannot exceed 15 mph for duration of test. 

11.	 Top speed of test drive cycle not to exceed 65 mph. 

12.	 Test trailer configuration must be a typical dry box semi-trailer, 53’ 

long, 102” wide, and 13’ 6” high. 

13.	 Trailers must be the same model and similar age, mileage and condition. 

14.	 Each trailer must have the same test payload. The combined weight of 

the trailer and payload must be approximately 46,000 pounds, +/- 500 

pounds. 

15.	 Test payload must be loaded over axle to be consistent with federal 

bridge laws. Payload must be secured so it does not shift during the 

test. 

16.	 Tires must be inflated to manufacturer-recommended maximum cold 

inflation pressure prior to start of test. 

17.	 Tires must be as similar as possible in size and condition, and have accumulated at least 500 miles wear-in prior to start of test. 

18.	 The tractor-trailer gap must be the same on both trucks, as measured 

from the back of the tractor to the front of the trailer. 

19.	 If testing a candidate tractor against a current SmartWay tractor model 

for the purpose of demonstrating SmartWay eligibility, the two tractors 

must have substantially similar drive train and power train configuration, including gear ratio, engine horsepower and size, transmission 

type, lubricant type, rear axle ratio, accumulated mileage, emissions 

aftertreatment system, etc. 

20. If testing trailer modifications or trailer aerodynamic equipment, test 

tractors must be equipped with features typical of line haul combination trucks – e.g., high roof fairing, side cab extender fairings, and 

aerodynamic profile. 

21.	 EPA must review and approve the test plan and the vehicle configuration prior to testing. 

SmartWay Transport | EPA-420-F-12-022 | www.epa.gov/smartway | 734-214-4767 | SmartWay-tech@epa.gov 
 

 

22.	 EPA reserves the right to review all test data and to 

reject any test it determines was not conducted in accordance with these provisions and / or SAE J1321, or 

otherwise not credible according to good engineering 

judgment. 

General requirement 

All provisions of SAE J1321 must be followed, in addition 

to the above EPA provisions. Trucks must be prepared and 

maintained according to SAE J1321, and results must be 

within SAE test minimum acceptable ratios to be a valid 

test. All measurement devices must be NIST-traceable. The 

fuel must meet all applicable ASTM standards for motor 

fuel for the intended application. 

The manufacturers will submit a test report to EPA that 

includes signatures from the test facility and manufacturer certifying that the testing was conducted in an 

accordance with the SAE J1321 as modified by the most 

recent EPA requirements. 

Testing Costs 

The manufacturer bears all costs for testing. 

Contact EPA 

Interested organizations should contact EPA prior to testing. To contact us: 

• 	 send an e-mail to: Tech_center@epa.gov or 

•	 write to Technology Assessment Center, US EPA, 1200 

Pennsylvania Avenue NW Mail Code: 6406J, Washington DC 20460. 

If you have questions regarding SmatWay Designated 

Tractors and Trailers or SmartWay verified technologies, 

contact the Technology Assessment Center at: 

Tech_center@epa.gov. 

SmartWay Transport | EPA-420-F-12-022 | www.epa.gov/smartway | 734-214-4767 | SmartWay-tech@epa.gov