Torque Shop
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Should I shift my car's transmission to neutral while waiting at the lights? There is less shuddering than if I leave it in the drive mode. How about when I am cruising or going down a slope?
If your car has an automatic transmission, you should avoid shifting the gear selector from drive to neutral during short waiting times such as at the traffic lights, despite a slightly higher vibration level.
The automatic transmission has a built-in hydraulic pump that is driven when transmission is in the drive mode. The pressurised hydraulic fluid ensures that the internal clutch is firmly engaged and contributes to the cooling and lubrication of the transmission. In the neutral mode, the pump is not driven.
You should never shift to the neutral mode while coasting at any speed or terrain. This is for safety, as you may need to power out of potentially risky situations suddenly.
Several new car models come with a fuel-saving feature which allows them to coast in the neutral mode. This is possible because their transmissions have a hydraulic pressure accumulator to ensure sufficient operational pressure at all times. So, they engage as soon as the accelerator is depressed.
If your car has a double-clutch gearbox, there is no danger in coasting with the lever in neutral. This is because the internals of double-clutch systems are similar to those of a manual gearbox and hence do not rely on hydraulic fluid pressure to maintain positive clutch function.
Shreejit Changaroth