PHEV stands for Plug-in Hybrid Electric Vehicle.
A PHEV has a battery and electric motor, but also has a petrol engine and transmission to supply power. The car can be refuelled by plugging it in to charge the battery or by adding petrol. The car decides what mode to be in at any time, and will run on petrol-only when the battery is empty.
Usually the battery will be smaller than the one in a ‘pure’ EV, giving a range of typically 15-30 miles on the battery only. For many commuters this may well be enough though.
See our blog post on the key differences between an EV and and a PHEV with the advantages and disadvantages.