You dont get 'out fer nowt'.. turn it up the high settings, and it will go like
a fookin rocket (mine does) BUT.. it drinks more fuel, feckin slurps it down!!
Get it on a sensible setting to suit you un yer pocket!!
I don't really get the point of using anything but the high settings. You don't use any more fuel provided you drive normally and the whole point in buying/fitting it is to have decent power for when it's required. It not like you can turn it up just for an overtake or to climb a hill. You just need to drive normally and economically as you would be if you were on a lower setting. Turn it up I say and control the amount of power/fuel used with your right foot.