Automatic Transmission (Overdrive)

[Octavius]

If you have the overdrive switch engaged (as in 'on') on an Automatic car � does this mean that all gears are selected and therefore revs can be reduced and thus fuel consumption should be better than if the auto gear box was using just 4 gears? Or does the reverse apply?

[chevrolet1.8]

i have had vehicles with auto boxes and overdrive including an american dayvan. i used to drive in overdrive all of the time with no bad effects and as it acts as another gear it does reduce the revs and so helps stop the engine labouring. remember that the sooner you get into top gear you will save fuel.

[DirtyHabit]

My 1997 and 2003 Crown Victoria's have overdrive auto that you can switch off, but I never do.