The power button tightens the shift point in the tranny. Does not effect fuel economy. I use it all the time on highway and city. I have seen a thread before that it gave a guy more. In this respect who knows. I believe it might promote better life and use in the tranny as the belts, pulleys (or whatever they call them) are under less use because of the quicker shifting. Tone in the accessory section actually sells a tranny module that does all the above but through the pressure mechanics in the tranny. Some might know more then me on this but this is what I believe to be true..... so keep the power button on.