This part of ISO 10521 specifies methods of determining the road load of road vehicles for subsequent test purposes, for example, fuel consumption tests or exhaust emission measurements. This determines the road load of a vehicle running on a level road under reference atmospheric conditions. It is achieved by either the coastdown method, the torquemeter method or the wind-tunnel/chassis-dynamometer method. This part of ISO 10521 is applicable to motor vehicles, as defined in ISO 3833, up to a gross vehicle mass of 3 500 kg.