Singapore's current electric vehicle (EV) and plug-in hybrid electric vehicle (PHEV) road tax framework has implications for mass-market family vehicles.

The progressive kilowatt (kW)-based taxation system is determined by electric motor output. Larger family vehicles, such as seven-seater multi-purpose vehicles (MPVs) and mid-sized sport utility vehicles (SUVs), typically require higher-output electric motors to move their heavier chassis and battery packs.

As vehicles are taxed solely on maximum motor power, family-oriented SUVs such as the Xpeng G9 are subject to annual road tax rates ranging from more than SGD 3,500 to SGD 4,300 (US$ 2,720-3,340). As a result, vehicles with higher motor outputs fall into higher road tax brackets.

Plug-in hybrids are also subject to the existing framework. Under the "whichever is higher" rule, a PHEV equipped with a higher-capacity electric motor is taxed based on its electric component, resulting in annual road tax liabilities exceeding SGD 4,100. PHEV owners also continue to pay fuel excise duties at the pump.

In addition, the SGD 700 annual flat additional component applies regardless of a vehicle's annual mileage or carbon footprint.

As Singapore advances its Green Plan, the Ministry of Transport may review these thresholds. Potential changes could include adjustments to the taxation formula to account for vehicle size or weight-to-power ratios as part of the country's transition towards cleaner transport solutions.