overdrive & fuel economy

[EK1]

would having the overdrive button on my 1989 camry result in better or worse fuel economy. thanks

[Mole]

If overdrive is off you wont use the final overdrive gear, if you cant use that gear you cruise at higher revs, constant higher revs means less fuel economy.

[Hiro]

Why are so many people clueless about overdrive and what it does? All it is is another gear with a taller ratio than 1:1 (ie for cruising). If you turn it off, then the gearbox won't select that gear and you'll be stuck in a lower gear.

If you want to relate it to a manual gearbox, imagine driving a 5-speed manual but never using 5th gear. You'll be doing higher revs on the freeway and thus use more fuel.

In short, unless you're hauling a load, the engine is cold or you want to stop the gearbox from "hunting" (constantly shifting up and down), then leave overdrive on and just ignore it.

[prometheus]

My Camry has an overdrive button that I always have on , but why do they even bother giving you the option of the button anyway ?

In what circumstances would you want to leave out your top gear when the gearbox is capable of doing the selecting for you anyway.

[Hiro]

In what circumstances would you want to leave out your top gear when the gearbox is capable of doing the selecting for you anyway.

In the situations that I mentioned above, for instance.

Sometimes it is better to hold a gear rather than shift up - this is why you might want to turn overdrive off when towing, because even though the speed might warrant top gear, the extra load that the trailer/caravan etc places could mean that the transmission will shift up, find that there is insufficient torque and then kick back down again, then shifting up due to speed etc etc, this is called "hunting" because the transmission is constantly hunting to find the right gear for the situation. In this case, it is better to turn overdrive off and just keep it in 3rd (if you have a 4-speed auto).

[prometheus]

Sometimes it is better to hold a gear rather than shift up - this is why you might want to turn overdrive off when towing, because even though the speed might warrant top gear, the extra load that the trailer/caravan etc places could mean that the transmission will shift up, find that there is insufficient torque and then kick back down again, then shifting up due to speed etc etc, this is called "hunting" because the transmission is constantly hunting to find the right gear for the situation. In this case, it is better to turn overdrive off and just keep it in 3rd (if you have a 4-speed auto).

Yes , good point.

[peregrine]

would having the overdrive button on my 1989 camry result in better or worse fuel economy. thanks

This has been answered pretty well in regards to load etc but also occasionally on potholed unmade roads or on some inclines where o/drive keeps popping on and off (or for that matter any other gear) it would be appropriate to change down to a lower gear to overcome that situation. The third gear in the auto is a direct drive and therefore I suggest should not cause any problems, check this out with a Toyota dealer who should be able to verify this if you wish to drive without o/drive for what ever reason. As to economy? Only one way to be sure with your driving style and that's do a check both ways. Not sure about your car but a falcon I used to own was six of one half a dozen of the other in and around town 60KPH areas. The Falcon without o/drive on would still lock up but I'm not sure about your car. HAPPY DAYS.

Edited January 18, 2010 by peregrine

[Wixy]

would having the overdrive button on my 1989 camry result in better or worse fuel economy. thanks

This has been answered pretty well in regards to load etc but also occasionally on potholed unmade roads or on some inclines where o/drive keeps popping on and off (or for that matter any other gear) it would be appropriate to change down to a lower gear to overcome that situation. The third gear in the auto is a direct drive and therefore I suggest should not cause any problems, check this out with a Toyota dealer who should be able to verify this if you wish to drive without o/drive for what ever reason. As to economy? Only one way to be sure with your driving style and that's do a check both ways. Not sure about your car but a falcon I used to own was six of one half a dozen of the other in and around town 60KPH areas. The Falcon without o/drive on would still lock up but I'm not sure about your car. HAPPY DAYS.

i also turn it off when i want engine braking, rather than using the brake themselves. theres this hill i constantly go down to and from work, its not long, but long enough to wear your breaks quicker than usual if im driving the same rd to work every weekday, all year. speed limit is 60, all i need to do is turn O/D Off and cruise down the hill WITHOUT pressing the brakes, and it stays at 60 for the duration. perfect slope to do so, love it, keeps me less concentrated on the speedo and more on the rd for those couple of mins. it doesnt exactly save fuel, but hey, when u have a camry youre not worried about economy cuz it is economy.

another means of using it is during traffic, if your constantly going from 0 to 60-75 and back to 0, the transmission works overtime going from 1st to 4th and back to 1st. and when your in 4th, and u want split second response from your throttle, being in 4th doesnt help that situation. if O/D is Off, more response can be gathered for overtaking delight.

Cheerios