[JimD]

Anybody know the specific instruction to change? I have used NCSExpert (which is neither real hard or real easy) and could probably make the change. But looking around for it would be time consuming.

I did a quick google search and found that Buick estimated 4-5% benefits in terms of gas mileage and AAA claims to have tested 3 vehicles and it showed 5-7% savings on the EPA cycle. A car and driver article says that the EPA averages the gas mileage with it on and off if there is a switch that reverts to on when you turn the car off. It does the test only with if off if the car will stay in that position when you turn it off. I think that explains why it reverts to "on". 5% would be between 1 and 2 mpg. While that isn't trivial, it assumes a specific driving pattern that may not be applicable (it is in the AAA article) and it also ignores the added duty on the starter, battery, and flywheel of all the additional starts.

At least BMW doesn't hide the coding like they do the speedometer "correction".