The Effective Ways to Use the Overdrive in Automatic Car

Overdrive in automatic car has come a long way since the improvement of the engine mechanism and highway transportation. The smooth roads and powerful cars encourage modern people to speed up on the road. 

But, auto manufacturers had to solve the challenge of creating gearing that can adapt to higher speeds without frictional loss to the rear. The gearing also has to maintain a lower RPM and put less strain on the engine. It’s when the overdrive gear came into the equation.

What Is Overdrive In Automatic Car?

Today’s automatic transmission cars with advanced transmissions, and electronic control often come with a semi-automatic mode, allowing the car to choose the most suitable gearbox in each type of terrain, even according to the habit of pressing the gas pedal.

But in the past, the technology was not as optimal as it is today, so on automatic gearshift levers, an O/D function may appear to assist. Currently, there are also some cars still equipped with this function, for those who love driving inspiration.

Overdrive or O/D, usually turned on and off at the touch of a button, offers the highest gear in the transmission in an automatic car. 

o/d off in car
Overdrive helps when you drive at more than 50mph. (Photo: Grafissimo)

It brings the RPM (Round Per Minute) of the engine down at a given road speed to facilitate better speed and fuel efficiency. It also helps your car to provide the best performance in higher-speed cruising.

In detail, overdrive is typically across-limit driving. The limit here is the gear ratio, at 1.00:1. O/D On means that the vehicle is allowed to run in gearbox mode with a gear ratio exceeding the limit of 1.00:1, O/D Off is limited to 1.00:1.

How to Use Overdrive in Automatic Car More Effectively?

Usually, cars having this gear have a dedicated overdrive button. Using it means locking it out and not engaging it. With the overdrive gear, the transmission goes through all the gears and then limits the functioning of the rest of the gears.

Below will be some notices on how overdrive in cars works at its best, both when ON and OFF. Let’s follow along!

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When Will The O/D Be On

Since this feature is quite uncommon on super modern automatic cars nowadays, they are still available on several lines.

what does overdrive do
This feature is quite uncommon on super modern automatic cars nowadays but still available on several lines. (Photo: Oards Automotive)

When the O/D is on (the O/D OFF light is not on on the dashboard), usually by default in automatic cars, it allows the gearbox to switch to the highest gear. This is when the vehicle is using the normal automatic gearshift function, and the engine RPM will decrease.

Overdrive in this case will result in quieter and smoother running with less overall engine wear by decreasing the amount of load on the engine. Moreover, this feature reduces engine wear and saves fuel.

Therefore, if moving normally on the smooth city road without obstacles on an auto transmission car, the O/D is always on, basically, whether you are noticing or not.

When To Deactivate O/D Gear (O/D OFF light shown-up)

Drivers should only actively deactivate O/D (O/D off light up on dashboard) often in situations such as slow traffic jams, accelerating quickly to pass, climbing high, going downhill… to take advantage of traction.

For the O/D off meaning, when the O/D function is deactivated, the vehicle will not let the transmission operate in the highest gear, but limit it to a lower gear to increase traction.

what is o/d off
As the gear mode with the O/D OFF light-up is only up to the level with a 1:1 ratio, the engine rpm will be higher. (Photo:

Here are the 2 situations you should take advantage of the O/D OFF in cars.

When you’re speeding up

It’s the textbook condition for using the overdrive in automatic car. When you drive at more than 60mph (50mph in the case of older vehicles), the RPM increases and the engine starts taking more strain. 

The OD OFF light will work like magic to take the pressure away from the engine and bring down the RPM.

However, don’t use it when you are speeding at less than 50mph or during city driving because the speed tends to be inconsistent there. The OD prolongs the life of your car’s engine and drivetrain only if you apply it wisely.

When you need to go downshift

The braking system has to take a lot when you drive downhill or get stuck in an extended traffic jam. 

Driving down a steep road requires you to put continuous pressure on the brake pedal while extended traffic requires sudden pushing of the pedal and speeding the car. 

If the O/D is deactivated in those situations, it will keep the RPM above idle without straining the brake and the engine.

what does o/d off mean in a car
Overdrive OFF lights up will take the pressure away from the engine when driving downhill. (Photo: Celtic Solar blogspot)

Overdrive In Automatic Car Vs. Manual Car

Both automatic and manual transmission cars can provide acceleration. And in both, overdrive serves as the top gear (with the lowest gear ratio). With automatic transmissions, O/D is usually an intuitive function initiated by the ECU when the vehicle reaches the appropriate speed.  

In a manual gearbox, overdrive is the highest gear, but it must be done by the driver. At highway speeds, the higher the gear, the more efficient the operation. 

Naturally, with a manual transmission, the driver plays an active role in acceleration by automatically shifting to the highest gear. But with automatic transmissions, the role will be opposite.

What Damages Can Be Caused by Incorrect Use Overdrive In Cars?

Overdrive in automatic car will both allow and limit your car to utilize the full range of the transmission to assist in every needed situation. It also helps with transmission life optimization and increasing fuel efficiency. 

However, if you use it incorrectly such as while towing a trailer, driving uphill, or speeding at less than 50mph, it will cause irreparable damage for your automatic vehicle.

So if you know how to use it proficiently, go for it. Otherwise, only use it when going downhill for safety. If you forget to turn it off, it is very harmful to the engine and gearbox, not to mention the fuel consumption. 

More details, it will burn out the transmission really fast, which is a costly fix as you have to spend something between $1800-$3500 or even more for the repair and reinstallation.

Check out this video from Vehicle Freak to learn more about overdrive in automatic car!