Been a fair talk about reducing electricity but what about fuel for the car. I have run our 2 litre diesel on supermarket fuel for a while and the stated MPG was around 34, now been using garages like Esso and Bp for a period of time and the stated MPG is 38 so just coincidence or what. I know supermarket diesel lacks certain additives but never would have thought it effects MPG because the engine management system cannot tell what fuel you are using, maybe if cylinder pressures were monitored then it could notice a difference but they are not. So to save fuel maybe running more non supermarket fuel could help, but really needs a more scientific approach so the drive cycles are more comparable and the savings may only occur on longer runs.