Save Gas by Turning On Overdrive (AT only)
Out of nowhere the thought just hit me. I wanted to know what use the overdrive button had on my Nissan X-Trail. Daryl told me before that you actually save on gas if the overdrive was off for city driving. However, after searching the web, I learned otherwise. So for those of you who don’t need the power, keep your overdrive on and you’ll actually get better mileage from your tank :-)
A short post from one of the answers in the forum:
“On the contrary, overdrive is for better gas mileage.
By definition, overdrive is a gear ratio less than 1:1. Which means the rpms of the outgoing shaft are higher than the rpms of the incoming shaft.
But it all comes down to is that the engine gets to run slower, therefore saving gas, when traveling at highway speeds.
Turning off the overdrive prevents the transmission from shifting into its top gear (usually forth) and will only go as high as third gear. The only reasons to turn off overdrive is when you are driving in hilly or mountainous terrain or are towing. The increased load of the tow and hills will make your transmission shift annoyingly in and out of overdrive to go up the hills or pull the tow load. So the button to turn overdrive off is there to stop this problem.
When traveling at highway speeds your car is normally in its top gear (forth is usually overdrive). When you stomp on the gas for acceleration, such as to pass, the transmission immediately shifts down to third gear to give you the speed boost you need. Overdrive can’t produce that kind of acceleration.” (via PMStern on Askville)
For those of you who want more information check out the following links:
