:In response to industry demands for a method to qualify fuels for their intake valve deposit (IVD) forming tendencies, the Coordinating Research Council (CRC) has developed an engine dynamometer test procedure. In Phase I, the 2.3L Ford engine was chosen as the focus test engine in comparison testing with two other high volume U.S. manufactured engines.1* A two-mode dynamometer test was developed in Phases II-A & II-B and shown to discriminate among the test fuels at a 95% confidence level.2In Phase III, both an interlaboratory study (ILS) of the two-mode dynamometer test and a vehicle fleet study were performed. The ILS was conducted to determine the repeatability and reproducibility of the test procedure and also to fulfill requirements for consideration of the test as an American Society for Testing and Materials (ASTM) standard. To determine how the dynamometer test relates to a typical on-road vehicle test using identical fuels, a four car study was performed using the ASTM D 5500-94 IVD Test Procedure following the completion of the ILS. This procedure is a derivative of the existing SwRI/BMW 16000 km vehicle test.3 The description and analysis of the Phase III program is the focus of this paper.