Which gear should an automatic transmission car use when going up and down long slopes?

[CalvinLynn]

The correct practice for an automatic transmission car going down a long slope is to shift from D gear to a low gear. Some automatic transmissions have an L gear, which stands for Low gear, designed for safety considerations. When descending a long slope, the L gear can utilize the engine's resistance to control the vehicle's speed, reducing the frequency of using the car's brakes and preventing the danger caused by brake fade due to frequent braking. Below are specific details about automatic transmission cars going downhill: 1. If encountering a short slope, you can simply stay in D gear and apply the brakes to pass. However, for long and steep slopes, keeping the automatic transmission in D gear and continuously applying the brakes can easily cause the brake discs to overheat, reducing braking performance and significantly diminishing the braking effect. Therefore, it's best to avoid this practice. 2. Nowadays, many models come with an M gear, which stands for Manual mode. By switching to manual mode and then shifting to 1st or 2nd gear, you can utilize the engine's low-gear braking effect, combined with intermittent braking, to control the vehicle's speed.