That is a pretty bad title. It should be hybrid cabs, not electric cabs, and - coincidentially - I was talking to a London cab driver a while ago about going electric and he reckoned that it would be terrible for business if the cab could not be charged overnight because the only thing that mattered to him was how much his cab would be on the road and his daily mileage comfortably exceeded the projected battery range of any electrical cab offering that he was aware of at that point in time.
Hence the petrol engine, which will more than likely be the main propellant for these cabs, so it is a nice PR move but let´s wait to see how many miles are actually driven electrically before we get all happy.