 In addition to the existing federal tax credit, plug-ins are eligible for a purchase rebate through the Clean Vehicle Rebate Project (CVRP).Also, zero emission vehicles (ZEVs) and Enhanced Advanced Technology Partial Zero Emission Vehicle (Enhanced AT PZEV), have been entitled to a clean air sticker that allows the vehicle to be operated by a single occupant in California's carpool or high-occupancy vehicle lanes (HOV).The limits for plug-in hybrids and expiration dates have been extended several times, and new rules went into force from January 1, 2019.