Which gear should be used for automatic transmission cars on highways?

[SanAnnie]

For automatic transmission cars on highways, you can use the S gear or D gear. The following are the speed regulations for highway driving: 1. Vehicle speed limits: The maximum speed for small passenger cars must not exceed 120km/h, other motor vehicles must not exceed 100km/h, motorcycles must not exceed 80km/h, and the minimum speed must not be lower than 60km/h. 2. Lane speed limits: For roads with 2 lanes in the same direction, the minimum speed for the left lane is 100km/h; for roads with 3 or more lanes in the same direction, the minimum speed for the leftmost lane is 110km/h. The minimum speed for the middle lane is 90km/h, and vehicles traveling at speeds above 60km/h but below 90km/h should drive in the rightmost lane.

[Viola]

When driving an automatic transmission car on the highway, I usually use the D gear. The D gear is the standard drive gear, which automatically shifts to the highest gear on the highway, keeping the engine speed around 1500-2500 RPM. This ensures low fuel consumption, reduced noise, and a smooth, comfortable driving experience. I often drive long distances, and with the D gear, the car remains stable without any drifting. The gear shifting process is seamless, allowing conversations inside the car to proceed undisturbed. If the road conditions are straight and flat, there's no need to switch to other gears—it's worry-free, effortless, and cost-effective. However, it's important to note that some people mistakenly shift to lower gears or manual mode, which can cause the RPM to surge and increase fuel costs. For novice drivers, sticking to the D gear on the highway is the safest option—don't overthink it, just focus on maintaining a safe following distance.

[OGage]

As a car enthusiast, I really enjoy using the S (Sport) mode for overtaking on highways. The S mode delays upshifts, allowing the engine to rev up to 3000-4000 rpm, with super-fast throttle response that delivers instant strong acceleration and that exhilarating push-back feeling when overtaking slower vehicles. For example, last time when racing with friends on the highway, switching to S mode made accelerating from 100km/h to 150km/h incredibly quick. But for normal cruising, D (Drive) mode remains the go-to, as keeping it in S mode would mean higher fuel consumption and more noise due to the elevated rpm. My advice is to make overtaking maneuvers crisp and clean, then immediately switch back to D mode to save fuel. Different car models have varying S mode calibrations, so it's best to test and find what suits you.

[McBradley]

In safe driving, using D gear on long downhill slopes at high speeds can easily cause brake overheating and failure. I switch to L gear or manual low gear, utilizing engine braking to slow down, with the RPM rising to high values to provide resistance, significantly reducing the burden on the brakes. Once on a mountainous highway, after descending a steep slope, I used this method and the brakes didn't overheat, giving me a great sense of security. On flat sections, I continue to use D gear and regularly check the brake system for maintenance.