 As part of the incentives to promote electric vehicle adoption, drivers of approved plug-in electric vehicles can use Maryland's high occupancy vehicle (HOV) lanes at all times, even if they are traveling solo.This incentive is in effect until September 30, 2017.Plug-in electric vehicles purchased new and titled for the first time between July 1, 2014, and July 1, 2017, are eligible for a credit up to , calculated as per kWh of battery capacity.