Fig. 2: Effects of different policies within the UTPM.

The policies can either increase (plus-sign) or decrease (minus-sign) the magnitude of variables, which are divided into inputs, constraints and outputs for the model. Fleet size refers to the level of activity of the fleet (size and usage), fleet performance refers to the energy efficiency per vehicle (or alternatively per km driven) and fleet type refers to the emissions intensity per Joule spent in the vehicle (which is dependent on the type of vehicle). Outputs are divided into energy demand (light blue) and emissions (purple). All policies decrease use-phase emissions, apart from manufacturing standards which decreases embedded emissions. Thus, each policy has potential to reduce fleet-wide emissions, and their behaviour and influence in the model is summarised here.