A three-point program is described which provides overall control of vehicle emission testing and assurance of acceptable product design. 1. Experimental design techniques are used in the test development activities to control test parameters and to insure sufficient test repeatability for test evaluation. 2. Test histories, established and automatically maintained on computer files, are continuously monitored to assure test control and to provide insights into the effects of various test parameters. 3. The objectives of each specific test request are analyzed and experimental designs utilized to develop test plans and procedures. Illustrative examples in each area are included.