The Overdrive gear, OD, works to force the RPM down at a certain speed, consequently improving the speed as well as the fuel economy. Besides, OD supports the car in providing the optimum performance while cruising at higher speeds.

What the Overdrive Gear does
The Overdrive gear, OD, works to force the RPM down at a certain speed, consequently improving the speed as well as the fuel economy. Besides, OD supports the car in providing the optimum performance while cruising at higher speeds.

When you should use Overdrive
Commonly, overdrive gear is activated by a dedicated button on the gearshift. Switching it on means LOCKING IT OUT, not applying it. When the OD is pressed, the transmission goes through all the gears and limits functions of other gears. To put it another way, the vehicle will downshift from the highest gear if you activate OD while traveling at high speed.

In normal drives, you should always lock the OD (again, to switch it on), thereby leaving the car shift to the top gear all automatically when necessary. However, overdrive gear can improve the performance of the car in certain situations, which are elaborated below.

When you are picking speed
When your car running at high speeds (above 60 miles per hour for new cars, and 50 mph for older ones), your engine is put under more strain with the RPM elevates. Activating the OD will effectively reduce pressure and at the same time bring down the RPM.

Note: OD should not be on in city drives where the speed is inconsistent or when you are at speeds lower than 50 mph.

When you need to downshift
The engine and the braking system are put under much stress when you are stuck in heavy traffic or going downhill. In traffic jams you constantly make sudden pressing on the pedal and speed the car, and you exert continuous pressure on the brake pedal while going down an inclined terrain. In such situations, the overdrive gear helps maintain the RPM above idle and make sure the engine and the brake won't be strained.

Watch guideline video at: https://naijauto.com/safe-driving/how-to-use-overdrive-gear-in-automatic-transmission-cars-687[size=8pt][/size]

Very importanter thread

For those who are fresh to the automatic world, you can also check this post on How to drive automatic vehicles in simple steps.

https://naijauto.com/safe-driving/how-to-drive-an-automatic-vehicle-in-simple-steps-574

Before you start

In most automatic cars, there are 4 modes for the gearboxes: D- Drive, N- Neutral, R- Reverse, and P- Parking.

Drive: The gears are selected automatically and work to drive the car forwards.
Neutral: It is similar to knocking a manual gearbox out of gear. Neutral mode is not advised when your car is moving (often referred to as coasting). You can use it along with the handbrake if you want to stop for a short time though.
Reverse: The name says it all, you are recommended to use this mode when getting your car backwards.
Park: recommended to be on as you stop and get out of the vehicle. With P on, the transmission is locked, which prevents the wheels from rolling (this mode should be selected along with applying the handbrake).

In several automatic gearboxes, the first gear or second gear can be selected. This option helps the motorist to keep the speed down in some situations (down a steep hill for example).
The option also works to keep down the revs and prevent the wheels from spinning as pulling away.
As when your car experiences highly slippery roads, you are recommended to take the second gear so that your wheel won't slipping.
There are also other automatics which allow you select gears manually via two ways: one is using the selector and another is using the paddles behind the steering wheel. By this, the driver gets more control.

The automatic gearboxes are invented to give motorists easier driving experience though it might bring perplexity when you start and stop your engine.

As you step into an automatic car, it should be left in P from the previous drive.
Press your right foot down on the brake pedal, start the engine by pressing the start button or by the key.
With your foot still stepping on the brake, station the shifter to D to move forward, or R to reverse. If you lift your foot off the brake, this will make the automatic cars creep forwards (this helps in low-speed traffic or parking).
It may call for more gas when the vehicle’s running on a hill or desire to move off more rapidly.
Once on the move, the gearbox automatically selects the proper gear and does it all for you.
After finishing your journey and your car’s stopped, keep your right foot on the brake pedal, shift to P, turn off the ignition, then get out of your car.

Mutemenot:
Very importanter thread

Thank you, we have a lot more useful tips to provide. Hope you like it! Here is another one!

What is the function of the neutral gear in automatic transmission vehicles?

1. What does neutral gear do?
First, what does neutral gear do in an automatic vehicle? The answer is it helps to disconnect the engine with the wheels, which means when you apply your pedal, no power will find its way to the wheels. Plus, when the car’s in neutral, the wheels keep rotating freely without the need of too many actions from the engine while giving you a certain amount of control over the car.
Basically, it’s not so detrimental to your vehicle when you shift to neutral except for some stress on the brake when you do so to stop the car. It should be noted that a constant practice of this in a long time may cause your torque converter to fail.

2. When do you need neutral gear?
a. Stopping your car when the throttle fails
As you are driving at high speed and panic to find your throttle gets stuck. What can you do? The speed is too hight so the brake is not enough to halt your vehicle. Fortunately, you have an additional option which is to use the Neutral gear, which contributes to the slowdown of the vehicle, then apply the brake to stop safely.

Some may think you can simply turn off the engine. However, doing so will abruptly cut off the power supply to the steering which may seriously harm your engine.

b. Stopping your car when the brakes fail
So what if your brakes fail to perform its deed? Many resort to turning off the engine. Don’t risk your safety doing that since it deprives you from control over the steering wheel. What's worse, it can even causes the wheel mechanism all locked up. But with the Neutral gear on, you can toggle between the lanes and find a safe place to park.

c. Asking for towing trucks in breakdown circumstances
Nobody wishes to let the towing truck draw their vehicle on road without the help of a tow dolly; however, if it is the case, Neutral gear should be credited for its job, which is the best way to keep your transmission less harmed.

Source: https://naijauto.com/safe-driving/what-is-the-function-of-the-neutral-gear-in-automatic-transmission-vehicles-684
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Hope the information is useful!