Interim Test Method for Verifying 

Fuel-Saving Components for SmartWay: 

Modifications to SAE J1321

 

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 carriers 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 describing how the Joint TMC/SAE Fuel 

Consumption Test Procedure – 

Type II (SAE J1321 Surface Vehicle 

Recommended Practice (October, 

1986) can be adapted as an interim 

test method to quantify the fuel 

consumption impact of fuel-saving 

equipment 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 > 1.5 miles (5 miles recommended).

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

4. Track surface must be completely dry and well-maintained; 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 as similar as possible on both pairs of 

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 configuraSummary of SmartWay 

Tractor & Trailer 

Program

SmartWay Transport | EPA-420-F-09-046 | www.epa.gov/smartway | 734-214-4767 | SmartWay-tech@epa.gov

May 2011
tions prior to testing. 

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 SmartWay prior 

to testing. To contact EPA: 

• send an e-mail to: SmartWay-tech@epa.gov;

• telephone the SmartWay Transport Partnership Call 

Center at (734) 214-4767; or

• write to SmartWay Transport Partnership, US EPA, 

2000 Traverwood, Ann Arbor, MI 48105. 

If you have questions regarding SmatWay Designated 

Tractors and Trailers or SmartWay verified technologies, 

contact the SmartWay Technology Team at: 

SmartWay-tech@epa.gov.

SmartWay Transport | EPA-420-F-09-046 | www.epa.gov/smartway | 734-214-4767 | SmartWay-tech@epa.gov