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Does The D3 Gear In An Automatic Transmission Have Any Unique Advantage?

ByMatsumoto Naoki-September 17, 2023

The popularity of automatic cars is on the rise, especially in the United States. The majority of Americans along with various other countries prefer automatic transmission to stick shift. Are you familiar with all the gears and their functions in these vehicles? Most people may know about the basic ones but some cars also have a D3 gear. What is its role in an automatic mechanism? Does it have any unique advantages?

What Is D3 Gear?

The D3 Honda Civic is the most common. A range of other makes and models feature the same gear but with different names.

In an automatic car, R (reverse), P (park), and D (drive) are the familiar gears. D refers to shifting the gear to the forward drive mode. In that mode, the gears will automatically change via hydraulics. Simply put, D is shown as a forward gear, when using this gear, the transmission will allow shifting from the lowest gear to the highest gear and vice versa. However, in order to be more flexible during operation for cars using automatic transmissions, car manufacturers have added a number of gearshift options such as D3, D2, or D1. The meaning of the number levels D1, D2, and D3 in automatic transmission cars will be the same as number 1,2,3 in manual transmission cars.

Under the D mode, there could be D2, D3, and D4 gear positions. They refer to several gear positions for a forward motion. In most cars, the D3 gear means forward motion but is limited to 3rd gear. In some other vehicles, it could refer to the position of the transmission in the third gear.

What Does D3 Mean In Automatic Cars?

The D3 auto means nothing else than downshifting in a manual car. In an automatic transmission, it is a lower gear that allows the engine to rotate at a higher rate to yield more back pressure than it can at a higher gear.

D3 works like downshifting in a stick shift. (Photo: bestcarmag)

Currently, the D is ‘overdrive’ in almost all vehicles – the main purpose of which is to save fuel. Driving the car in this gear rather than the lower modes means you can have nearly 15% improved gas mileage.

In short, the D3 gear utilizes the first three gears in an automatic transmission or locks it on the third gear. It will move to a higher gear when the vehicle reaches the highest RPM. It also does an amazing job of maximizing the RPM range for every gear according to the required power and pull.

The Unique Benefits Of D3 Gear

D3 is a low gear in automatic transmission cars (typically Honda), used in cases of uphill, heavy load, and downhill, and especially useful when driving in the city. Engaging to the D3 is likely to provide several advantages in different driving conditions. Let’s find out how you can make the best use of this gear when driving an automatic car:

Going downhill

Many truck drivers apply to downshift when they drive down a slope or hill. It reduces the pressure on the braking system and prevents the brakes from overheating.

You can apply the same trick when driving an automatic vehicle. In that case, apply the D3 to reduce the stress on the brakes while going downhill. You can reap the best benefit of the gear by using it when your car is going down with a heavy load. However, doing so will affect the mileage because the engine runs at a higher RPM. Also, doing it frequently can wear off the transmission.

Driving uphill or in the snow

The gear also comes in handy when you are climbing a hill or driving on a slippery surface. The transmission keeps shifting between gears in these conditions. Engaging to the D3 prevents slippage from gear shifts, helping you avoid getting stuck on a hill or in the snow.

When you are driving upward to a hill or on a slippery road covered in ice, slowing down the car by applying the brakes may cause the vehicle to get stuck there. Also, shifting the gear may cause it to lose traction, which could be highly dangerous. In those situations, the advantage of locking the transmission in a given gear appears to be a blessing.

For faster acceleration

Many people think that they cannot accelerate quickly when engaged in the D3 gear. Well, it is a wrong concept. You can easily do it by pushing the accelerator pedal, which allows the transmission to go downshift automatically.

Hauling load

When you are towing a trailer or another vehicle, you have to carefully control the speed. However, frequent applications of the brakes are not good and may deteriorate the braking system. Engaging to the D3 gear will limit the speed to the third gear, which is ideal for cruising. You can also apply the same trick during heavy rainfall when you may need to slow down often.

Use D3 when you are driving in the city. (Photo: caranddriver)

Read more:

Ideal for city driving

You can also use the D3 for city driving when the speed is less than 50km. since the D or fourth gear is suitable for highway cruising, locking it up on D3 in and around town is the best practice. Using the third gear while driving at a low speed will help you to achieve a higher rev to which the car will respond better. Leaving the gear in D while you are driving in the city means overwork for the transmission. It will have to shift from the fourth to the third gear when you need an extra jump.

Watch this video to understand more about the D3 gear:

Matsumoto Naoki is senior car blogger at Car From Japan. Having background in mechanical engineering, he has a unique perspective on a lot of new car innovations. Prior to Car From Japan, Matsumoto was Mechanical Design Engineer at Yajima Plant, Subaru Corporation. His articles provide detailed DIY instructions and how-tos to help you get your new car on the road. If you want to save money and feel more confident when working on your cars, you should not ignore Matsumoto’s sharing posts. He presents driving tips and tricks for everyone through easy-following steps and mechanically but friendly writing.

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