This International Standard describes a dynamic dual-task method that quantitatively measures human performance degradation on a primary driving-like task while a secondary task is being performed. The result is an estimate of secondary task demand. The method is laboratory based, and this International Standard defines the method, the minimum requirements for equipment to support the method, and procedures for collecting and analyzing data derived from the method. The method is applicable to all types of interactions with in-vehicle information, communication, entertainment and control systems; manual, visual, haptic and auditory, and combinations thereof. Secondary tasks requiring speed variations to be performed cannot be tested with this method. It applies to both Original Equipment Manufacturer (OEM) and aftermarket in-vehicle systems. It also applies to systems either portable or integrated into the vehicle. The driver behaviour principles, the specific task procedures and driving task correspond only to the operation of a passenger car.