This document presents a clean draft proposal for the 04 series of amendments to UN R51 (Noise of M₁-M₃ and N₁-N₃ Categories of Vehicles). The proposal establishes uniform provisions for sound emission approval of motor vehicles with at least four wheels, introducing comprehensive specifications for measuring vehicle noise during motion and stationary conditions. Key provisions include detailed test methods with outdoor and indoor testing options, sound level limits varying by vehicle category and power characteristics, requirements for vehicles of categories M₁ and N₁ to comply with Real Driving Additional Sound Emission Provisions (RD-ASEP), specifications for exhaust silencing systems containing fibrous materials, conformity of production procedures, and specific adaptations for vehicles equipped with Automated Driving Systems. The regulation applies from its official entry into force, with a transitional period allowing acceptance of prior-series approvals until a specified date.