What is overdrive and when to use it (and when not to use it)
Many vehicles with automatic transmissions are equipped with an “overdrive” gear that is the highest gear available. Selecting the overdrive gear reduces the engine speed while it is engaged.
Typically, you do this when you want to maximize fuel economy while maintaining a constant speed on roads with minimal gradients.
When this happens, the engine will sound less loud than usual and the engine will slow down so it doesn’t have to work as hard and will use less fuel.
What is overdrive in a car?
If you want to engage overdrive, you won’t find a gear among the other letters on your shifter. There is no letter “O” that stands for overdrive like you would select when going forward or reverse. Instead, there’s an overdrive button, usually located on the side or near the shifter. Simply press this button to engage the overdrive gear. The transmission then downshifts from the highest gear to every other gear.
This is because the engine is prone to slowing down when the vehicle is constantly traveling at high speeds. This improves engine performance and reduces fuel consumption.
If you regularly drive on highways with high speed limits or other flat roads, you will get the most benefit from the overdrive feature. In an automatic transmission vehicle without overdrive, the driver must achieve the desired speed with a normal shift pattern that prioritizes performance over fuel economy. This puts more stress on the engine and therefore uses more fuel. However, automatic cars with overdrive switches may sacrifice power and performance for fuel economy.
When not to use overdrive
There is some debate about the minimum speed at which the overdrive function can be used. Generally, if you are traveling below 50 mph, you should not engage the overdrive gear. It is difficult to maintain such a low speed when using the overdrive gear. The engine speed will not be at a single speed, but will vary erratically and become quite unstable. This can make the vehicle’s driving condition very dangerous.
When driving over hills or passes. In such cases, the engine needs enough power to maintain speed while fighting gravity.