In this paper, zero-emission heavy-duty vehicles refers to vehicles with maximum weight ratings greater than 3.5 tonnes (t) that are equipped with powertrain technologies that produce no tailpipe emissions of greenhouse gases and air pollutants. ZE-HDVs are battery-electric and hydrogen fuel-cell vehicles. This paper will cover freight-carrying heavy-duty rigid trucks and tractor-trailers. Buses are outside the scope of the analysis.