In order for the economy mode to be used, it must have been programmed by the coach builder. It is available on the Allison transmissions that is found on a lot of MHs. In my case, I have an Allison 3000 powered by a 350 HP Cummin diesel. My tranny is not programmed for the economy mode. A lot of people have said that they have not noticed any difference when using the economy mode. I believe, as stated above, that the only good time to use is when you are on level ground, like traveling in Florida for example, and can have the cruise on. Otherwise, it will not really do anything for you.
Dave and Karen -- '02 Ultimate Advantage 36 C, 350 HP Cummins, Allison 3060 Tranny
'07 Ford Escort, Brake Master 4160, '13 Ford Edge, InvisiBrake