Fuel Economy
Testing & Evaluation
Additional trucks and test laps can be added to a program to improve repeatability and confidence of final testing and evaluation results.
The Society of Automotive Engineers (SAE) fuel economy testing and evaluation procedures used to generate fuel economy results accepted by the U.S. trucking industry have been conducted at Southwest Research Institute (SwRI) for more than 25 years. These fuel economy tests include:
- SAE J1321 Joint TMC (Technology & Maintenance Council)/SAE Fuel Consumption Test Procedure Type II)
- TMC Procedure RP 1109
- SAE J1264
- SAE J1376
- SAE J1526
- Interim test method for verifying fuel-saving components for SmartWay; modifications to SAE J1321
The J1321 and RP 1109 procedures specifically address the needs and operating conditions of long-haul truck fleets.
The other SAE Recommended Practices (J1264, J1376, and J1526) are more appropriate for testing and evaluating fuel consumption during operating cycles representative of bus, pick-up and delivery, and refuse operations.
The Fuel Economy Testing and Evaluation Procedure
The minimum test scope consists of a control truck and two test trucks driven in a baseline segment and a test segment. If two engine oils were being compared, oil A would be installed in the control truck and each test truck during the baseline segment. During the test segment, engine oil B would be installed in each of the test trucks. Additional trucks and test laps can be added to a program to improve the repeatability and confidence of the final results, which are stated as a percent of fuel economy improvement of the test item compared to the baseline condition. Additional segments can be added to the program to evaluate more than one test item.
A Fuel Economy Test Example
For a J1321 program with Class 8 trucks, SwRI will lease tractors and trailers unless the client furnishes the test vehicles. Leasing agencies will typically have trucks available that are powered by Caterpillar, Cummins, or Detroit Diesel engines. Fuel consumption is measured by simulating a long-haul route, utilizing weigh tanks for fuel consumption measurement.
EPA SmartWay™ Experience
SwRI successfully conducted the U.S. Environmental Protection Agency (EPA) SmartWay program from October 2005 to April 2006 for the EPA in support of the SmartWay Transport Partnership with the goal of reducing emissions and improving fuel economy in the transportation sector. SwRI performed fuel economy and NOx evaluations on two different class 8 truck and engine configurations using the SAE J1321 protocol. A total of 38 J1321 test segments were conducted. The tests were conducted with 4 drive cycles, which were defined by the EPA and simulated on an oval test track.
The SmartWay test program was designed to evaluate:
- Fuel economy and NOx impact of single wide tires
- Diesel oxidation catalyst (DOC)
- Trailer aerodynamics on 2 types of heavy-duty diesel engines in 2 different class-8 line-haul trucks
Portable In-Use Emissions Measurement Service (PEMS)
EPA emissions regulations require in-use emissions testing to measure the success of low emissions engine technologies during real-world vehicle operation. To meet this requirement, SwRI offers in-field testing services using a portable emissions measurement system. PEMS can be customized during installation to meet specific client needs and/or individual vehicle hardware requirements.
- For information about how SAE J1321, CEC M111, and ASTM Sequence VIB test procedures compare for assessing heavy-duty engine lubricant fuel economy, visit hdfueleconomy.swri.org.
Related Terminology
fuel testing and evaluation • fleet economy testing • drivetrain component • J1321 • RP 1109 • SAE recommended practices • bus, pick-up, delivery truck fuel consumption • PEMS • in-use emissions measurement • EPA SmartWay program • SmartWay certification
