With increased emphasis on comparing interior noise performance levels of passenger cars, multi-purpose vehicles, and light trucks, a need existed for the establishment of a recommended practice for making interior sound level measurements. Many variables, such as environmental conditions, instrumentation and vehicle test parameters exist that make accurate comparisons of vehicle interior sound levels difficult at best.The new proposed SAE Recommended Practice J1477-XXX8X, Measurement of Interior Sound Levels of Light Vehicles, establishes a procedure for making vehicle interior sound level measurements. Environmental conditions, instrumentation set up and analysis, and vehicle test conditions are described in detail.A round robin test was recently conducted to validate the procedure. Four auto companies and one acoustical material supply company participated. Each company, using this SAE procedure, measured five vehicles that ranged from a full size car (RWD) to a sub-compact (FWD) and one light duty truck. Results showed good comparisons of interior sound levels.