The Development and Proposed Implementation of the ASTM Driveability Index for Motor Gasoline

An ASTM Task Force developed a Driveability Index (DI) model that is being considered for inclusion into the ASTM D 439 Standard Specification for Automotive Gasoline (1)*. The DI is a property of hydrocarbon gasoline that incorporates the gasoline's 10, 50, and 90% evaporated distillation temperatures. The DI equation is based on the results of cold start driveability testing conducted by six laboratories on many vehicles. Tests were run at ambient temperatures ranging from −5 to 70 degrees Fahrenheit (F). A unique analysis method using median car results to combine the data from the different laboratories was used to develop the DI equation. Different DI limits were proposed for each of the five ASTM D 439 volatility classes. The proposal also included increasing several maximum distillation temperature limits in D 439.