Is it a good idea to use the Overdrive after a certain MPH to save Gas?

Question

Choose the best possible answer that answers yes:

A.) Should I keep my vehicle off of overdrive all the time?

B.) Should I keep my overdrive on all the time?

C.) Or Should I have my overdrive off until I get over 45MPH and then turn my overdrive on.

Answer 1

If you have a manual/shift transmission, leave overdrive OFF unless you're doing freeway (not stop-and-go-) driving at over 35 or 40 mph. Overdrive is for speed and efficiency (lower engine rpms). When towing or going uphill,  don't use overdrive.

If you drive an automatic transmission vehicle, leave the shifter on OD, the auto-trans will automatically go to the gear needed, included OD.

Answer 2

If economy is your thing, than keep it on all the time.

If power, like pulling a trailer or climbing a hill is what you want, then switch it off. I don't know why you would ever want to do number three. I read my manual in my Ford truck and it says leave it on except for towing and steep grades.

Answer 3

Your question doesn't cover auto trannies. In an auto transmission, the overdrive is . . automatic.

But absolutely, if you get over 45 MPH and the engine is not under stress (as in going up a hill) O.D. will save you a lot of gas on long trips.

The gear ratio in the "fifth gear" (overdrive) is higher than the top gear, so you get less revolutions of the engine in proportion to revolution of the wheels for the same amount of expended energy. However, the gear ratio is too high to efficiently run the engine under stress. When you need to pass, or go up a hill, drop down to high gear (likely 4th gear.)

If it's an auto tranny, you do nothing at all, the pumps in the transmission and engine RPM decide it for you.