What does D123 gear in a car mean?

[VanMariana]

D gear is the normal forward gear of the car, and 123 refers to the low gear mode of the transmission. The following is a specific introduction to the automatic D123: 1. D1 gear: D1 gear is the heavy-duty gear. The transmission stays in first gear. 2. D2 gear: The vehicle starts with D2 gear. The transmission stays in second gear, used for starting on slippery roads or as a limiting gear when moving slowly, avoiding gear shifts between 1st and 2nd or 2nd and 3rd gears. 3. 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.

[KhloeLee]

When driving an automatic transmission car, the D gear is the normal forward driving gear, while the D123 gears actually represent manual gear restrictions. I always pay special attention to this when driving on mountain roads. For example, when going down a long slope, shifting to D2 or D1 gear allows the engine to help slow down the car, preventing the brake pads from overheating and failing. Using D1 gear when climbing steep slopes is particularly effective—the car feels like it's supercharged with energy and won't roll back at all. These gears aren't usually needed for city driving, but when starting on icy roads or muddy terrain, D2 gear can help reduce tire slippage. Every automatic transmission driver should know these small functions—they can be lifesavers in critical moments, especially for those driving older cars who need to be extra mindful of these operations.

[VanIan]

I used to wonder what those numbers on the automatic gearshift were for, until I realized they're actually for manually limiting the gears. The D3 gear locks the transmission within 3rd gear, which is especially suitable for winding mountain roads, preventing the transmission from upshifting suddenly during sharp turns and causing power interruption. If you get stuck in mud at a construction site, just switch to D1 gear—the engine torque is fully unleashed, making it easy to get out. However, don't randomly use these limiting gears on regular flat roads, as it wastes fuel and wears out the transmission. These designs are quite user-friendly, allowing automatic transmissions to precisely control power like a manual transmission in special road conditions.

[DeMiles]

Novice drivers of automatic cars may not pay much attention to the numerical markings next to the gear shift. In reality, D1 is essentially a forced first gear, which is particularly stable when starting on a 45-degree steep slope, and the situation of rolling back is basically non-existent. I often use D2 gear on long downhill sections, where I can go for seven or eight kilometers without touching the brakes, keeping the speed steadily controlled at around 40 km/h. Nowadays, many cars come with paddle shifters, and these physical gear buttons tend to be overlooked. However, I believe that physical gear shifts are more direct and reliable, providing an extra layer of safety, especially when driving in rain or snow.