What Does OD Mean in a Car?

At the top right corner of your car’s dashboard, there is an indicator primarily on red or yellow as OD off. If you do not see it, it means it is on. What does this imply, and how does it affect your driving experience or car use? Below we have looked into this in detail, its functions, advantages, and disadvantages, if any, to your car.

What is OD?

OD is simply the shortened form of overdrive. It features on your transmission as the last but highest gear. The OD refers to the extra high ratio the car producer uses for cruising. In general, it means any gear with a ratio lower than 1:1.what is od - overdrive in a car

It is present in all modern cars, whether automatic or manual. The first record of using this mechanism is from way back in the 90s. A piece of separate machinery was attached to the engines for this purpose.

Its design works best on the highway where there is a need for speed, safety, efficiency, and a level of comfort. Its application is most useful for long free roads.

Read More: How to Calculate Gear Ratio

How Does it Work?

It works by providing a mechanical advantage that makes your engine run at lower rates/speeds when you are on high speeds.how does OD work - overdrive

At overdrive, your car cruises at a uniform and sustained speed. The efficient cruising can be from either gearbox ratios or high final drive. Also, it can be a combination of both, depending on the manufacturer.

Your engine works at a reduced RPM, turning about its axis at a lesser number of times per minute. In layman’s terms, this means the times your car wheel rotates is more with every single rotation of your engine.

This reduction in revolutions per minute defines the speed you are at. It works more efficiently and economically, translating to many short- and long-term benefits for your vehicle. Many vehicles which operate on automatic transmission usually enter into OD mode when your driving speed reaches a particular number.

The speed may start at about 40-45+ mph. Note that this depends entirely on the vehicle model. For manual vehicles, it will be beneficial to also turn on overdrive when your speed reaches this average on the highway.

While shifting gears, it is relatively easy to engage your OD. In more recent car productions, the overdrive is mainly a button tagged O/D or OD on your shifter that you can quickly press.

Should I Drive With OD On or Off?

While you can manually put it on and off, experts recommend letting your car enter into overdrive when it wants to. For newer-age mechanics, your vehicle can easily detect when it needs it or not. So this is not something to worry about.Should I Drive With OD On or Off

There are many advantages to having the overdrive turned on. Let’s look at some of them:

  • It helps reduce your vehicle’s fuel use: Using this feature on your car increases its fuel efficiency. This fuel reduction in fuel is the OD’s mechanical advantage. It is the ultimate benefit of having your overdrive on. Many systems are in place to improve the fuel economy and its use effects. Only a few produce practical results and show sustainability. Among these is the use of overdrive. Тhere are no exact figures to quantify the amount of fuel you save from your overdrive use per square mile. However, it is pretty significant as it cuts down costs and is environmentally friendlier due to lower emissions. Hence, the name of some car models is Eco.

This benefit is especially helpful when you drive long distances on highways. You can use less gas or whatever fuel your car operates on per mile.

  • Quieter Driving: Using an overdrive helps reduce the noise levels of your car. – Also, it keeps the vibration and harshness (NVH) to a more tolerable level. This is very helpful for cars that operate from powerful engines. The engines of a vehicle are the top contributor to the overall noise, vibration, and harshness. These come during the work processes. Slower and less work will reduce the processes that generate the NVH level thus, it will partially decline. Therefore, using your overdrive gives you the benefit of a quieter and more serene car drive.
  • Lower Wear and Tear: using overdrive gears reduces the speed of your engine rotation significantly. This reduction can range anywhere from 10 to 50 %, which is tangible. There is a reduction in work, thereby extending the lifespan of your car’s engine. Your engine does not heat up as fast and does not wear out as quickly. These both translate to better efficiency at lesser incurred costs from repairs.

Should I Leave OD On or Off?

If your overdrive is still on at low speeds, or you find it annoying, it is still not a problem. And your car will keep working smoothly. However, keeping it on does not drain the car’s battery or engine. There are no downsides to you leaving it on. Also, there is no adverse effect to keep it off, except for losing out on the benefits it brings.

Nonetheless, at times you will need to turn the feature off. If you have the car manual, you will find the manufacturer’s recommendations on when you want or need to turn it off. Regardless, if you are not sure, here are some situations where you may want to keep your OD off. After such cases, you can put the overdrive back on and enjoy its benefits.

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When Do I Turn it Off?

It will be safer and more efficient to be in a lower gear when driving in the following cases.

  • Heavy Car Workload: This is probably the most common situation we advise disabling your overdrive. Overdrive is efficient and advisable only if your car functions at a standard capacity. Implying that going into cruise mode brings no effect. If your automobile is doing heavy work like carrying tons of weight, towing a truck or similar, check for the O/D off sign. Using OD reduces the torque of your vehicle. If you are pulling, you will need a lot of it.
  • Ascending a Gentle or Steep Terrain: When climbing up a sloped terrain, your car will need to build up torque while operating in third gear. If your overdrive is on, your engine may fleet between the two, interfering with this process. Some steep slopes, like speed breakers, can also sometimes fall under this category, depending on the vehicle.
  • Descending a Steep Terrain: You can climb up a hill while gaining enough torque. On the other hand, improper brake use on the way down requires a different approach. If your overdrive is on while you descend from steep places, you may want to use only the brakes. However, this makes them work harder and heat up. Repetitions of this can cause unnecessary wear and tear to them. If your OD is disabled, you can use manual engine braking that is more robust. Engine braking means both your brakes and the engine work together to slow the car down. This will save you the need for relying only on the former.
  • Trouble in Car Movement: Sometimes, cars may not necessarily encounter steep slopes to start behaving erratically. If your car is experiencing problems while moving, like changing gears or stalls, try putting it off. This can also help when you need to overtake another vehicle, and putting it off may make it more sensitive to your foot force. As stated earlier, overdrive works best on clear, accessible, and open roads, ideally a highway. Relatively constant speed contributes to efficiency.
  • Winter: Not limited to snowfalls, including rough and uneven terrains that reduce the car’s ability to gain traction. If your automobile is on overdrive in such situations, you may find it hard to keep your drive smooth. Your car may need car spin off the road or lose control. It is important to note that car brands are not the same. Some cars, especially newer ones, usually have better traction control and other features that help mitigate the result of overdrive. So, while this factor may depend on your car construction, we advise you to consider it.

How to Turn Off OD

All the situations mentioned above can make it problematic for cars on automatic overdrive. Understandably, sometimes you may not have the time to change gears. For example, when going up a gentle slope. New-age cars, however, are brilliant, and the driver has not much work to do.How to Turn Off OD - overdrive

Most cars can identify when you are going up or down a hill. Thus, you can keep it on almost 100% of the time. Also, you do not need to turn it off manually. Nonetheless, suppose you are using an older model, and it can’t be as fast. In that case, there are alternate options to help your car detect its need to function on lower gears. An example of this action is by firmly stepping on the gas pedal.

While some cars have the button or gear with the acronym OD, some don’t. Instead, it is present as an Eco button, generally the highest gears available. Whether your vehicle has it or not, shifting to a lower gear will disable the feature.

Does OD Make a Car Faster?

No, having your overdrive on does not make your car run faster. Its mechanism causes your car engine to work less while maintaining your speed. This does not increase or decrease your car’s speed in any way. The speed remains the same while the efficiency increases.

What is OD on Automatic?

When you turn on most automatic cars, the overdrive (OD) is on by default. This action differs from what you get with a manual car. The manual overdrive must be manually engaged for it to work, usually with the lever that we also call a shifter. Further, your vehicle will automatically use the OD as the functioning gear in automatic cars when it gets to a high speed.

Can the Overdrive Gear Get Faulty?

The overdrive indicator should naturally be invisible if it is on. The indicator should only show its off status when you disable it or shift to a lower gear in manual cars. However, there are some times when your overdrive indicator may be blinking erratically. This may be a cause of concern.Can the Overdrive Gear Get Faulty

Firstly, check to see if it is fleeting between that gear and a lower gear to gain more torque in movement. This happens only when driving, and it resolves itself quickly. However, if you are not moving, it is disabled. Also, it may be on, but you are not at a high enough speed for it to be in effect. Meaning it may be faulty.

A faulty overdrive poses no harm to your car, and it is repairable by a mechanic. During non-usage, there will be lower fuel efficiency, faster engine wear, and less quiet rides at high speeds.


The OD on your car refers to a vital gear that helps increase your car’s efficiency and health. It operates both on automatic and manual transmission and can easily be disabled. You can keep it on as it does not harm the car systems. However, at times it is better to turn it off. To conclude, it is a great feature that goes unnoticed, especially in newer age models.