What does D123 in automatic transmission mean?

[DeDominic]

D gear is the normal forward gear of the car, and 123 refers to the low gear mode of the transmission. Here is a detailed introduction to the D123 in automatic transmission: D1 gear: D1 gear is the heavy-duty gear. The transmission stays in first gear. D2 gear: The vehicle starts in D2 gear. The transmission stays in second gear, used for starting on slippery surfaces or as a limiting gear when moving slowly forward, avoiding gear shifts between 1st and 2nd, and 2nd and 3rd gears. D3 gear: D3 gear is the overtaking gear. It can be used as a limiting gear when traffic is not smooth, avoiding gear shifts between 3rd and 4th gears.

[LeDamian]

Seeing numbers like D123 on an automatic transmission can indeed pique curiosity. Having driven for over a decade, I most commonly use them for speed control during long descents. For example, when navigating mountain switchbacks, shifting to D3 locks the car in third gear, utilizing engine braking to reduce brake pedal usage and prevent brake pad overheating failure. During slow-moving traffic jams, switching to D2 makes for smoother driving, otherwise the transmission constantly shifts between 1st and 2nd gear, creating jerky movements like riding a horse. Recently when driving a friend's SUV up a steep slope, using D1 provided exceptional stability with no tire slippage whatsoever. Note that these gears aren't meant for racing—they're primarily for handling special road conditions and protecting the transmission. Remember to press the shift lock when changing gears; you can simply push the lever while driving without braking (a common question from beginners).

[LunaAnn]

A student asked me about the difference between D-/D+ and 123 next to the automatic gear lever. Actually, the principle is similar. 123 refers to low-speed gear limits, where D3 means it will only shift up to 3rd gear at most. Last winter after a snowfall, when I was driving my child to school and the road was icy, I switched to D2 to start, as the lower torque in 2nd gear makes it less likely for the tires to slip. It's also best to use a fixed gear when driving through waterlogged sections to avoid frequent gear shifts by the transmission, which could lead to water ingress. A mechanic once reminded me that using D1 for long periods on steep slopes may accelerate clutch wear. Here's a lesser-known fact: when driving a hybrid car in B mode, the kinetic energy recovery is at its strongest, creating an effect similar to the drag feeling of low gears in a gasoline car. Using these gear limits properly can indeed save both trouble and the car.

[LaIsabela]

Last week I accompanied my relative to pick up his new car and noticed him staring blankly at the gear shift. Here's a simple analogy: D mode is like a fully automatic washing machine, while D123 is equivalent to semi-automatic mode. Especially when driving CVT models, stomping the accelerator often results in engine roar without corresponding acceleration - switching to D3 delivers more immediate power. I've developed the habit of downshifting to D3 before highway overtaking; revving to 4000 rpm makes acceleration remarkably crisp. I remember during a mountain trip, using D2 for downhill sections proved much more stable than braking, saving brake pads while preventing heat fade from prolonged braking. Just remember not to sustain high RPMs in lower gears too long, as it may trigger engine protection protocols.