The ISO 20566-2020 standard specifies a test procedure for the determination of scruf resistance of Paints and varnish coating systems by the laboratory car washing method. The method is particularly suitable for evaluating coating performance under simulated car wash conditions using swirl/spin brushes and synthetic dirt in a laboratory environment. The test results can be used to compare the car wash resistance of different Coating systems, including Coatings and Protective Plastic films used in the automotive industry. The third edition of this standard revises the terminology and test conditions, removes the specific requirement for the temperature of wash suspensions and introduces a method of verification using plastic panels. ISO 20566-2020 was developed in collaboration with ISO/TC 35 Technical Committee, SC 9 Subcommittee, and the European Committee for Standardization (CEN), under the technical cooperation agreement between ISO and CEN.