Text prepared by the Chairman of GRB to introduce provisions for a new test method regarding the sound level of motor vehicles, as requested by WP.29 at its 136th session (TRANS/WP.29/1041, para. 74).

This document proposes to maintain the current test method in the first part of Regulation No. 51 and to insert the new test method in a second part in order to put Contracting Parties in the position to collect data on the new test method. The provisions for the new test method are based on document GRB/2005/2/Rev.2.