Enlarge / Fleets looking for a medium-duty electric truck now have a new option. (credit: Motiv) Medium- and heavy-duty vehicles account for about 23 percent of US vehicle emissions. That's much less than the amount of greenhouse gases emitted each year by light-duty vehicles, but if anything, businesses can often have a clearer case for electrification, whether that's to save money on annual running costs or to meet ESG goals.