The overdrive gear in your transmission was specifically designed to lower the strain on the engine at higher speeds while traveling on relatively flat roadways. Introduced as a replacement to three speed transmissions, the automatic overdrive transmissions became standard equipment on most American vehicles during the late 1970s and early ‘80s. While many people will just put their car in overdrive from the start and never take it out, there are times where traveling in overdrive is actually detrimental to your drive train, and your fuel economy.
Shift the car into overdrive when you are travelling on flat or fairly level roads. Place it in OD before you even start moving, as the automatic transmission will shift itself into the appropriate gear based on throttle response and current speed.
Shift the car down into a lower gear when climbing hills. Imagine the overdrive is tenth gear on a ten speed bike. If you try to ride a ten speed up a long hill in tenth gear you will exhaust yourself long before you reach the top. The same concept applies to your transmission. Downshift it when climbing hills so that the engine and transmission can have an easier time climbing.
Shift back into overdrive once you are traveling on level ground again. Most production vehicles are designed to get optimum fuel mileage in the highest gear while traveling at approximately 55mph. The engine does not need to work as hard in overdrive and if it does not work as hard, it will give you better fuel mileage.
Tips & Warnings
- Other ways to save fuel include making sure your tires are properly inflated (check the air pressure every two weeks), maintain clean air and fuel filters, avoid full throttle acceleration when possible and avoid driving faster than the posted speed limit on freeways.
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