Passenger First Aid is a gadget introduced in the Battlefield Hardline: Robbery expansion. Similar to the MEDICAL UNIT specialization in Battlefield 4, it allows Operators to heal teammates while they occupy the same vehicle, regardless of whether they are driving or not. Like Stunt Driver and the Tactical Tool Kit, the gadget is passive and only functions when riding or driving in a vehicle.
The gadget can particularly be useful during Hotwire rounds inside an objective vehicle, as it will keep the the occupants healed when under fire. This is especially helpful if working alongside a Mechanic with a Repair Tool, as the vehicle and its passengers will be able to kept in the fight for much longer.