Many car owners have such a driving habit when driving, whenever they are waiting for a red light, they will choose to switch from D gear to N gear, and then pull the handbrake to stop, after the red light becomes green, let go of the handbrake to hang D gear to drive, these habitual driving methods, are despised by many car owners, they think that the transmission can not frequently switch back and forth between D gear and N gear, is this statement correct?
I have consulted some old drivers, and the reason why they do not recommend switching back and forth between D gear and N gear is entirely due to two considerations, one is not conducive to improving the service life of the transmission, and the other is not conducive to improving the fuel economy of the vehicle. Seemingly perfect answer, in fact, full of loopholes, as an automotive practitioner, I will give you an analysis!
Does it reduce the service life of the transmission?
As a mechanical component, the transmission has a certain life, if the owner switches back and forth between D and N gears, this will make the transmission withstand undue impact, thus affecting its service life. If you hold this view, your idea is absolutely superfluous, the function of the transmission is to transmit the power of the engine to the vehicle tires, it can keep the engine in the best condition, either to maintain the optimal power, or to maintain the most economical fuel consumption, the working attribute of the transmission is gear switching, as long as the transmission is in service, the gear shift is essential.
The switching of each gear of the transmission is achieved by changing the meshing and disconnection of the clutch, while the meshing and disconnection of the clutch is controlled by the solenoid valve switch, whether it is the wear resistance of the clutch, or the number of solenoid valve switches, it is after many durability tests, in other words, the clutch and solenoid valve of the transmission can not be damaged at all. Owners who are worried that the "frequent switching of D and N gears" will damage the transmission, your ideas are a bit redundant.
Will it increase the fuel consumption of the vehicle?
Other car owners say that frequent switching back and forth between D gear and N is not conducive to improving the fuel economy of the vehicle, which makes some sense, but it is not very comprehensive.
Now the vehicle, generally equipped with automatic start and stop function, the vehicle in the D stop state, the engine will automatically turn off, if the owner switches to N gear at this time, automatic start and stop to lift, engine idle rotation, it is obvious that this is not conducive to improving the fuel economy of the vehicle. If the engine automatic start and stop is not working, the transmission in the D gear stop, equivalent to the position in the 1st gear, the input speed of the transmission is zero, and the engine idle rotation, the output speed of the engine is idle speed, at this time, the hydraulic torque converter between the transmission and the engine, its input and output there is a speed difference, which will consume the energy of the engine, which is not conducive to improving the fuel economy of the vehicle.
But with the advancement of technology, many vehicles have made corresponding improvements, such as automatic start-stop function, as long as the vehicle is in a parked state, whether the transmission is in N gear or D gear, the engine automatic start and stop are working; in addition, when the vehicle stops in D gear, the transmission will enter the neutral control mode, the input of the transmission is not zero, but the engine output speed, in this case, there is no loss of ability due to the speed difference inside the torque converter. If your vehicle is equipped with these technologies, the fuel consumption when the transmission is attached to D gear is the same as that when it is attached to N gear.
In the past, the reason why the owner frequently switched the D gear to the N gear, it was nothing more than to save effort when parking (in front of the red light), the owner did not need the D gear to continuously step on the brakes, but now the vehicle is equipped with autohold function and automatic start-stop function, the emergence of these functions, but also make D stop parking possible, the owner does not need to step on the brake, when starting to accelerate, the owner can directly step on the accelerator to accelerate. Therefore, the owner now does not need to switch gears frequently between D and N.