Transmission System - Other

What does Overdrive Mean on an Automatic Car

Nidhi Nangia
By Nidhi Nangia. July 13, 2017
What does Overdrive Mean on an Automatic Car

Automatic cars have become more popular and in-demand among car drivers over the last few years. They are easier to maneuver, and the driver can drive conveniently without fighting with the gears. They are easier to drive for novice drivers as well. If you have also got a new automatic car, you must have noticed that it still has a number of gears that show which gear your car is driving in. You must have seen an overdrive button as well. This oneHOWTO article is going to shed some light on what does overdrive mean on an automatic car.

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  1. What is overdrive used for?
  2. What happens when overdrive button is on/off?
  3. How does overdrive work?
  4. When to use overdrive in an automatic car
  5. Benefits of using overdrive
  6. Conclusion

What is overdrive used for?

Most automatic cars run on four speeds, and have an additional gear of overdrive. Basically, this 5th gear intends to lower your car’s rpm, which is the revolutions per minute at which your car engine is running. Subsequently, overdrive provides better gas mileage for highway cruising. If you turn on your overdrive, your car will enter that 5th overdrive gear automatically. If you don’t turn it on, your car will continue running in 4th gear and you will end up exhausting more fuel. In addition, using overdrive will also save your brakes when you slow down, as the process of braking will be done with less revolutions, thus making your brakes wear slower and will last longer.

What happens when overdrive button is on/off?

When your overdrive button is active and the light is turned off, your car’s transmission goes through all the gears of the system, including the highest gear which is overdrive. This gear is successfully used to overtake, tow and climb hills. When you press the overdrive button, the overdrive off light will come on. Now, your car won’t go into overdrive gear and your car’s performance will be limited to its three gears only. This leads to a downshift from your highest gear when you are speeding and you have pressed overdrive button.

How does overdrive work?

Overdrive has an epicyclic gear train located behind the car’s transmission unit. It may couple the output shaft direct to the input driveshaft, or enhance the speed to make it turn faster than input shaft. Then you can say that output shaft has overdriven to the input shaft. Overdrive speed is basically a result of integration of planetary and epicyclic gearsets into the car’s transmission. Automatic cars have electronic overdrives in which computerized systems automatically adjust to the load and power requirement conditions of the car.

What does Overdrive Mean on an Automatic Car - How does overdrive work?

When to use overdrive in an automatic car

Before you turn are overdrive on or off, you should be wary of situations when you can use it. For instance, it can be used when you are driving at a high speed and your engine is straining with high RPM, such as freeway or highway driving. But it is not the right button to press when you are driving in a city, or if you are running at the speed of less than 50, that too inconsistently. Typically, you would like to turn off the overdrive when you require a sudden downshift from 4th gear to 3rd, such as while overtaking. When used appropriately, it will prolong your car’s engine and exert less strain on your drive train.

Benefits of using overdrive

When you use overdrive, your car’s engine speed reduces, which results in fuel saving and wear reduction. Over the last few years, almost all vehicles, both automatic and manual, have included overdrive in their models. All car engines have a peak performance level, and overdrive can be helpful in keeping your engine away from this range. If applied at appropriate speeds, you can save fuel even while driving at low speed.

Moreover, using overdrive correctly, such as on highways, can reduce the amount of pollution emitted by your car to up to 1/3 less than it would with a normal gear.

Using overdrive can also benefit several of your car's accessories by improving their lifespan. These accessories that will get a longer life are: the steering pump, the air conditioning compressor, the smog pump, the water pump, the alternator.

The amount of noise pollution inside the car is reduced as the engine will run smoother.

What does Overdrive Mean on an Automatic Car - Benefits of using overdrive


Overdrive has a lower input speed than the output speed. The speed increases instead of decreasing. When you engage the overdrive, you improve your car’s efficiency and save fuel as well. The turbine stays disconnected from everything, and the only inputs that comes is facilitated by converter housing. All in all, this gear allows your car to run at high speed while keeping your engine slow and nice.

If you want to read similar articles to What does Overdrive Mean on an Automatic Car, we recommend you visit our Car Maintenance and Repair category.


  • You should note that, although there are plenty of advantages of using overdrive, your car will have less power if you sue it while going uphill.
  • Turn off your overdrive when you're hunting or towing. Moreover, you should also turn it off when you're on little downgrades when using the engines' brakes.
  • Do not use the overdrive in slippery roads or snowy/rain road conditions.
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What does Overdrive Mean on an Automatic Car