A plug-in hybrid electric vehicle (PHEV) works in a similar way to a self-charging hybrid– there is a combustion engine that works with an electric motor and a battery. A plug-in hybrid has a larger battery than a self-charging hybrid car. This allows the car to be powered just by it’s battery for limited distances, but you also have the combustion engine should you be travelling on a longer journey. Typically, a PHEV can travel between 30 & 40 miles on its battery power.
In the same was as a Hybrid vehicle, a PHEV can be charged a little while driving, but for the full benefit, you should plug in to charge the battery. Typically, a PHEV can have the battery fully charged in around 3 hours.