You should leave the OD switch on all the time for regular driving.
Your car will automatically shift into top gear if necessary, regardless of your selection.
However, there are some conditions when pressing the overdrive gear can improve the car’s performance.
Is it better to drive with overdrive on or off?
The more you use the highest gear (or overdrive), the better the gas mileage. If you have an automatic transmission with both a “D” (Drive — or sometimes it’s labeled “3”) and an “OD” (Overdrive), you can and should generally leave the gear selector in OD and let the transmission figure out what’s best.26 Apr 2015
What does turning off overdrive do?
This is because the engine needs less gas when going at lower RPMs. The better fuel efficiency at tops speeds is why most people say to leave overdrive on. Another benefit of overdrive is that it helps with breaking. That is because the car can shift out of the top gear when you slow down which will help you slow down.
What is overdrive and when should I use it?
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When to Use Overdrive | Ken Garff Automotive Group – YouTube
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What is the purpose of overdrive in an automatic car?
Generally speaking, overdrive is the highest gear in the transmission. Overdrive allows the engine to operate at a lower RPM for a given road speed. This allows the vehicle to achieve better fuel efficiency, and often quieter operation on the highway.