Came across this link on CNN about a guy going into business selling a kit to “hack” or modify your Prius.
The kit apparently replaces the NiMh battery with a (greater capacity) Lithium Ion one, and also allows the car to be plugged in to a power point to charge it up. (For the Prius newbie’s, this is not the way they normally work - Priuses (or Priii? 
) charge themselves up when breaking and coasting, or by diverting power from the petrol engine).
Great idea! Some of my car-mad friends with hotted up cars have long delighted in buying modified engine management chips that squeeze more power out of the engines. This guy is modding a car to be more fuel efficient!
Obviously, some of the “green points” are lost if your house gets its electricity from a coal-powered generator plant - whenever you plug the car in to charge it up, you’re still polluting…indirectly. But if you subscribe to one of the green programs on offer, where your electricity provider sources your power from renewable sources like wind, its all good.
Interestingly, the story has Toyota being quite supportive of this kind of thing. Makes sense - as the manufacturer you want to encourage your customers to build a community around your vehicle and take it further.