For the purposes of this question a low carbon vehicle can be a plugin hybrid, a purely electric vehicle, a hydrogen powered vehicle, or any other that doesn't directly generate significant amounts of carbon emissions. The average vehicle generates 300-400 g CO2 per mile driven so any vehicle generating less than 40g CO2 per mile driven should qualify (with the caveat that combustion-engine vehicles running on gasoline that aren't plugin hybrids will never qualify).

Passenger vehicles as defined by BTS or closest available https://www.bts.gov/content/new-and-used-passenger-car-sales-and-leases-thousands-vehicles