The CNOSSOS-EU road noise model described in EU Directive 2015/996 makes use of model coefficients that represent the average noise emission spectrum and speed dependence for each particular vehicle category. Separate coefficients are provided for the road surface influence and for accelerating/decelerating at intersections. Appendix F provides default values for cars, trucks and two-wheelers with combustion engines. This study describes a method to establish noise emission coefficients and road surface corrections for a new vehicle category. The primary aim is to include (hybrid) electric vehicles in the noise assessments, to enable evaluation of EV/HV proliferation scenarios. To separate rolling and propulsion noise, a combination of pass-by (CPB) and close proximity (CPX) methods on an appropriate selection of instrumented vehicles is proposed. Acceleration and deceleration coefficients may also be derived from instrumented vehicle measurements. The total noise emission is calibrated using roadside measurements on vehicles in regular traffic. Acoustic transfer functions are calculated to derive the sound power coefficients from the measurement results.The methodology provides an approach to adding any vehicle categories to CNOSSOS-EU, and for a potential future BSI standard to replace the existing British CRTN assessment method. Recommendations for further development of such a standard are given.