What gear to use when going downhill with an automatic transmission?

[DelDallas]

Generally, use the low gear (L gear) when going downhill with an automatic transmission. If there is no L gear, switch to manual mode if it is a manual-automatic integrated transmission and use a low gear. Below is some relevant information about automatic transmissions: 1. Automatic principle: The engine's power is transmitted through the gearbox, which is also a key factor affecting fuel consumption. Generally, an automatic transmission consumes over 10% more fuel than a manual transmission. Whether manual or automatic, more gears mean better fuel efficiency. 2. Driving tips: For manual transmission cars, upshift at higher RPM. The engine is designed to operate at higher RPMs, and parameters such as dynamic balance and rotational inertia of various components are also designed with high RPMs as the reference. If the engine operates for a long time under non-optimal conditions, the load and wear on internal components naturally increase, leading to frequent vibrations and knocking, and affecting lifespan. Choosing 3000 RPM as the upshift point ensures that after upshifting, the engine operates at around 2300 RPM, keeping it within a healthy RPM range.

[VonElle]

I've been driving for over 20 years, and automatic transmission downhill driving deserves serious attention. What I feared most when driving on mountain roads was long descents—keeping it in D gear while braking, only to find the brake pads softening halfway, which always gave me a cold sweat. Now I've wised up: before descending, I switch to L gear or a lower gear in manual mode, letting the engine control the speed without constant braking. For particularly steep slopes, I use 1st gear; for gentler ones, 2nd gear—this trick works wonders on long descents. My experience is to downshift before the descent; waiting until the car speeds up to shift might damage the transmission. Once, driving a friend's new car equipped with hill descent control, pressing a button automatically managed the downhill speed—but most cars still require manual operation. Remember, safety first: don’t let the brakes overheat.

[DiEli]

For automatic transmissions on downhill slopes, two key factors matter: gradient and distance. On steep slopes, always shift to a lower gear marked L, 1, 2, or S on the transmission to engage engine braking. For instance, coasting over 3 kilometers downhill in D gear is a recipe for disaster—your brake discs will overheat and smoke. I once witnessed an accident in mountainous terrain caused by prolonged brake failure due to constant braking. The technique is simple: ease off the accelerator before descending, gently apply brakes to reduce speed, then smoothly shift to a lower gear. Check your owner's manual—some sport models allow manual downshifting via paddle shifters. Rain or snow? Shift earlier—engine braking provides more stability when tires lose traction. Pro tip: never force a downshift above 60 km/h.

[DiHector]

New drivers often ask how to operate an automatic transmission when going downhill. In fact, avoid just staying in D mode! Switching to L mode is the most worry-free option. For cars without an L mode, switch to manual mode and shift to 1st or 2nd gear. The principle is that lower gears limit the engine speed, preventing the car from accelerating uncontrollably. For short and gentle slopes, D mode with light braking is sufficient, but for long and steep slopes, always use a lower gear. Once, when I was driving a friend's car down a parking garage, I shifted to 1st gear and slowly coasted down without needing to brake at all. Remember to slow down before shifting gears to protect the transmission. Modern cars are very smart—some SUVs come with a hill descent control feature where you just press a button, but older cars still require manual operation.