As more drivers opt for automatic transmissions, there is a fair amount of confusion as to what the various gear designations actually mean.
While not all vehicles have a D3 gear in the gear selector, it can be found in some models. What does D3 gear mean in an automatic car and should you be using it?
In this article, I cover what D3 gear means and some benefits you can expect. I’ll also discuss the right way to use D3 when you are driving.
What Does D3 Mean in a Car?
D3 is advantageous when driving down or up steep hills. D3 uses the first three gears of the vehicle’s automatic transmission, locking it into 3rd gear as the highest option.
D3 is employed to provide more power in certain driving circumstances but provides much more RPM range for each gear.
Most automatic cars have the standard set of gears such as P (Park), R (Reverse) and D (Drive). For normal driving, the shifter is simply set in D, and nothing else is thought of. While the vehicle is in Drive, the gears will shift automatically because of hydraulics.
Some cars have other options below the D gear, which may be labeled D2, D3, and D4.
These show you the maximum gear position the car will go to while driving forward. For example, D3 is limited to 3rd gear, but it will also use 1st and 2nd gears.
D (Drive) gear is the overdrive gear. It is ultimately developed to save fuel and to provide more efficiency in normal driving situations.
D3 Gear Driving Advantages
#1. Reduces Brake Wear.
In the D3 position, your vehicle will slow down on its own. Because of this, you will not have to use the brake pedal often (especially when descending a hill).
While it is not that expensive to change brake pads, you shouldn’t have to wear them out. Traveling down a steep grade? Consider shifting the transmission into D3, allowing the engine to perform some of the work.
#2. Better Throttle Response.
When you pull out into heavy traffic, you can utilize lower gears to get higher RPMs to build speed more quickly. The D3 function also works well when driving around in the city, as you don’t require high speeds, but rather quick throttle response.
Again, running your RPMs at redline, is not good for the car; consider moving back to Drive to allow more longevity for the motor.
#3. Safer Driving Dynamics.
When you drive in D3 mode, you will gain better control of vehicle dynamics. You would notice this more when driving in rainy conditions, when the vehicle is most prone to slipping.
Since D3 allows you to run at lower gear ratios, the car wheels would not be able to spin up to fast giving the drivetrain more traction.
Using engine brakes also allows for other kinds of safe driving dynamics to when making your way down steep grades. The engine automatically holds the vehicle back to limit speed while going downhill, reducing the chances of excessive speed.
Best Times to Use D3 Gear
#1. Travelling Downhill.
Truck drivers are familiar with descending a steep hill. They routinely use engine braking to help slow the vehicle down. You can do this with D3 too.
D3 relieves pressure from the braking system and the pads won’t overheat. This prevents damage, and the engine controls speed as the lower gear is engaged. But, if high RPMs are sustained too long, the engine will also wear out.
#2. Driving Uphill.
D3 may come in handy if you are looking to go faster going uphill. Because D3 keeps the transmission from shifting into overdrive you are able to run higher RPMs that equal more speed.
You also don’t want to run the transmission hard in any driving situation. You may get the car up to speed and the RPMs are very high, it’s best to put it back in overdrive.
#3. Driving on Slippery Surfaces.
It is easy to lose traction on a slippery road. D3 helps your vehicle to maintain control and more importantly helps you from slipping gears.
D3 keeps your vehicle from shifting into a higher gear, you are less likely to be stuck during bad weather. It allows the wheels to work together to get traction to get you out of bad conditions.
#4. Accelerating Fast.
If the transmission shifts too early, gaining the acceleration needed to pull into the traffic is difficult. You might push down on the gas, but it barely feels like the vehicle is gaining any speed.
With D3 engaged, the vehicle won’t shift into higher gears, causing the RPMs to rise more quickly to help gain acceleration.
#5. Carrying Heavy Loads.
You need to pay attention to vehicle speed when hauling cargo or towing, but you don’t want to ride the brakes because that causes them to overheat and fade.
When a vehicle is in D3, the maximum speed will be based on what is available in the third gear. Typically, this will be plenty of speed for regular driving while supplying more control in the vehicle with weight.
How to Use D3 Gear in an Automatic Car
If you are ready to utilize D3 in your automatic vehicle, here is the process:
- You can start out in Drive (D). The car will take off and use its lowest available gear. When you get to a point where you want to prevent the transmission from going any higher in gear, set the gear shifter to D3.
- You can switch from Drive to D3 whilst driving. In some cases, you merely disengage the overdrive button and force your vehicle into lower gears and, at other times, you will see the D3 symbol on the gear shifter itself.
If the RPMs get too high, be sure to switch the transmission back to Drive. You do not want to add unnecessary wear to your engine or transmission.