This document describes a fuel-consumption test procedure that utilizes industry accepted data collection and statistical analysis methods to determine the difference in fuel consumption between vehicles with a gross vehicle weight of more than 10,000 pounds. This test procedure can be used for an evaluation of two or more different vehicles but is not to be used to evaluate a component change. Although on-road testing is allowed, track testing is the preferred method because it has the greatest opportunity to minimize weather and traffic influences on the variability of the results. All tests shall be conducted in accordance with the weather constraints described within this procedure and shall be supported by collected data and analysis. This document provides information that may be used in concert with SAE Recommended Practices J1264, J1252, J1321, and J2966 as well as additional current and future aerodynamic and vehicle performance SAE standards.
The previous SAE J1526 document lacked statistical analysis of test data and lacked constraints on test criteria required to resolve small fuel consumption differences. Additionally, results from previous versions of this procedure have been reported without a confidence interval. To address these limitations, it was determined that a full revision of the document was required. Moreover, to simplify this procedure, all references to evaluating components have been removed. Refer to SAE J1321 Type II for component evaluations.