Driving on hilly back roads cruising around 45-50 it's nice to have the overdrive OFF because the torque converter will stay locked in 3rd gear, providing a nice direct feel. If you leave the OD on, the converter doesn't really stay locked in 3rd gear, and it likes to shift into 4th gear with an unlocked converter, providing the "slushbox" feel. FWIW, my od off light is burnt out, but the button does function correctly. I have to remember whether I turned it off or not, which isn't much of an issue because it's usually only turned off on the road leading to my house, which afterward the car is shut off.