What does overdrive do?

What's the advantage of openning it? I always wondered what that damn button does.

This post has been edited by LeonStryfe: Feb 28, 2007 - 8:55 PM

Overdrive allows you car to go into 4th gear. If you turn it off then you are only allowing your car to reach 1st, 2nd, and 3rd gear. With it on you allowing your car to go to1st, 2nd, 3rd, and 4rd gear.

The user manual says for better gas mileage leave it on. You also wanna leave it on when your on the expressway

OD is just the 4th gear. turning it off makes your car a 3 speed. it just disables 4th gear, thats all. leave it on. only reason they let you turn it off is if say for example you are on a curvy road and you car keeps going from 4th to 3rd and back. you would turn od off to avoid the excessive shifting.

This post has been edited by celicaST: Feb 28, 2007 - 9:03 PM

wow, never knew that. Now whenever i'm on the parkway maybe my car won't be at 4,700 rpms going 80... because its always in 3rd! I always thought OD was worse on gas... **goes off to kick himself**

Wow >_> i too didnt know that, I thought that thing locks it to third gear.

Overdrive sounds like it would take up more gas... lol.

having it on n off has its advantages n disadvantages...leaving it off will leave u with more power.....lets say ur in traffic n u have od on when u want a more punch to the brakes push it off so that it "downshifts" for engine to slwo down hence teh name "engine braking"..leaving it on will let u have more mileage to the tank...ive tried both ways on one tank...

od on: 283 miles local plus highway
od off: 250 miles local plus highway

*more gas mileage because you wont be in high rpms in third gear
srry to jack the thread, but don't manuals get better gas mileage than autos because they have that fith gear? ive heard mixed opinons

Not on our cars. the manual's 5th gear leaves you at 4K RPMs @ 80MPH whereas the Auto's 4th Ratio [not gear technically] leaves you at roughly 3K RPM @ 80MPH [IIRC from my 95 GT Auto]. This is also why having your O/D on gives you better gas mileage at freeway speed than with it off [it does I promise - that's really the point of it].
Also if you take off from a stop with the O/D off the tranny will hold the shifts longer allowing you to reach higher engine speeds depending on throttle position sort of simulating what you would do with the manual. It's basically an attempt at making the autos more peppy like the manuals. There is a big diff between GT Manual and GT Auto. I've had both and that's the only reason I sold my 95 Auto - too damn slow.

This post has been edited by Negative: Mar 1, 2007 - 12:45 PM

http://en.wikipedia.org/wiki/Overdrive_%28mechanics%29

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thats the first thing I noticed about highway driving after the tranny swap. you still get almost twice as much gas mileage with a manual. it just isn't because of the gear ratios.

my guess was that the auto tranny is so much heavier, has the torque converter, and uses a lot more electricity and brainpower from the ECU.

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ALSO depends on your driving habits. If your "speed racer" (which im sure no one here has ever speed before ) your obviously gunna use more gas up than a "granny" would