Do not shift gears to the neutral position while driving if you have an automatic transmission car. This can cause lack of fluid lubrication and cooling, damaging the automatic transmission It can lead to another operation safety problem, affecting the braking distance which may lead to a severe accident.
It is recommended to avoid sliding at a neutral position while driving a manual transmission car, especially in long downslope distances. This may make an engine flame out in case of an emergency. The emergency braking distance is affected due to no engine braking, which may lead to an accident. Some drivers think that driving at a neutral position can save gasoline. However, the ECU (electronic control unit) of a car will calculate the spraying oil according to the input signals of plentiful sensors. Stepping on the clutch pedal (or neutral position) in sliding, will not stop the ECU from spraying oil but will spray oil according to the idle mode. The ECMU will cut off oil based on different working conditions in sliding at a position and stop spraying oil, so the oil consumed at a neutral position is more than oil consumed at other positions. The manual transmission car can shift to a neutral position in case of parking.
A car will not speed up sliding as expected on a downslope distance; it will keep the speed or slow down. You may even need to step on the accelerator because the engine can assist with braking. This can prevent the reduced braking effect of a high-temperature braking disc from leading to an accident on a long downslope distance. Therefore, it is normal to step on the accelerator on a downslope distance for more secure driving.
After the adaptive cruise control is enabled, a car will automatically brake and keep a certain distance from the detected front car as needed. If the front car moves at a faster rate or changes to another lane, the car rate will restore to the previously set cruise rate. At this time, the car will automatically accelerate. You should stay in control of the steering wheel and operate the system if needed.