> The gross vehicle weight rating of the NGDV with an ICE, including payload, is 8,501 lb (3,856 kg),[2]: Table 3-1.2 just one pound over the EPA's threshold to be considered a heavy-duty truck, allowing it to avoid more stringent pollution emissions and efficiency standards for light-duty trucks.
Source: https://www.vice.com/en/article/the-new-usps-trucks-would-pr...
Not sure if that's still valid (obviously not for the electric versions), but that is actually insane.