Phev is only a stepping stone to full electric which will be introduced over the coming years. The scheme will lag the “outside world” lol by a year or so. Battery production is the limiting factor for many manufacturers but once they can provide the number of batteries for the number of cars manufactured full BEVs will be the most common cars on the road. This is likely to be towards the end of this decade but if battery science continues at the speed it has in recent years it could be sooner.