Before explaining whether to step on the accelerator, we need to know what the idle torque of the engine is. The so-called idle torque can be simply understood as: on the flat ground, when we put on the reverse gear and release the brake, the vehicle will reverse itself without stepping on the accelerator. At this time, the engine output force is idle torque. Under normal circumstances, the idle torque of the engine is very small. For example, when we reverse the car, we only control the speed by controlling the brakes, not stepping on the accelerator. Then when there are pebbles or slopes under the wheels, the car may not be able to walk. At this time, we can hear the engine running, but the car won't go. The reason why the car can't walk is that the idle torque of the engine is too small to climb this ramp. At this time, if you want to continue reversing, you must step on the accelerator and increase the engine torque.
The reason why the idle torque of the engine is so small is also considering the fuel economy of the vehicle. Generally, the idle torque of the engine is only used to maintain the operation of the engine itself and the power supply of some electrical appliances on the vehicle, and then it is increased by 20% to enable the vehicle to walk at idle speed, so the idle torque will be very small. But generally speaking, the idle torque of manual gear is greater than that of automatic gear. For example, if we learn manual gear in driving school and use the first gear to back into the warehouse, the speed will be very high without stepping on the accelerator, so we should control the speed by braking. The reason why the idle torque of manual transmission car is large is that manual transmission car has clutch. If the torque is too small, it is easy to cause the engine to stall. Automatic cars are different, because there is a torque converter as a buffer, or the dual-clutch gearbox will automatically control the semi-linkage state, so the engine will not stall without much torque when idling.