The owner's manual advises switching on except in a few specified instances.

Would you agree, or is it just for situations where you might anticipate grip difficulties?

Any impact on mpg?

Thanks

From what I understand it is permanently in the ON position. You have to switch it off manually but it will go back to the ON position each time you leave the car.

Doesn't effect MPG either.

Can't cope with rain, bumps, corners, junctions or just about any situation when power is applied either. Really not worth it in my opinion. Just bogs the car down and makes you lurch everywhere.

There has to be some pretty amazing weather for me to leave it turned 'ON' put it that way