This is the correct answer.

Karmakid: Wikipedia is also correct. What u got confuse is whether O/D is on or off. If u read Wikipedia's paragraph carefully, it is referring to O/D=On for lower RPM and save fuel.

I'm not sure about old cars or cars in US, but i think most cars here is default O/D=ON. like my Kia Sephia, default O/D=ON. So it allows you to go to a higher gear, saves FC and lower RPM.

If u set it to off, it's like forcing the auto transmission to NOT USE the highest gear, thus allowing ur more power temporary to overtake, etc.

DO NOT SET YOUR OVERDRIVE OFF UNDER NORMAL CIRCUMSTANCES FOR LONG PERIOD. if you set it OFF for prolonged period, your auto tranny/engine will die faster...i think i read it somewhere...

This post has been edited by Matrix: May 7 2007, 03:24 PM

IMO, Shifting to gear 2 is quite useless...only useful when coming down from Genting in order to slow down ur car without excessive braking.

Last time i tried to put 2 to go up genting...useless...then i put O/D off only it performs normally. IMO, just put O/D off and let the ECU determine ur gear ratio instead of forcing it to a fix gear.

But of course, it could be my KIA behave like that...

New car...dun go Genting yet!!! Maybe after 5K then try...but don't blame me if u stress ur engine...a friend of mine last time went up with relatively new Kelisa (not so new...maybe around < 1 year),,,after that she said engine very loud noise already...

If go to genting, better go halfway and take cablecar....dun kill ur car prematurely! Lots of nice car parking there at the cable station also...Benz, BMW...and Myvis of course.

"It's easier to understand overclocking a CPU than overdriving a gearstick"-Confucious


ok, Ok, Confucious didn't say that, but i just thought it's nice phrase...