The button on the lower panel beneath the ECON button is the on/off switch for the sensors - however, it turns them ALL off (or on). The Stop/Start feature is OK- saves some fuel, but not a great deal I wouldn't have thought. Most of my driving is m-way, and when on short runs, I disable the Stop/Start as its just a needless strain on components. But yes, turning the A/C off makes a massive difference to MPG. I don't use the A/C - only once a week to check the system is working properly etc, but daily use - no. This rain ridden island can never truly get hot enough to warrant the use of A/C.