Will an automatic transmission car move when in D gear without pressing the accelerator?
4 Answers
An automatic transmission car will move when in D gear without pressing the accelerator because automatic transmission vehicles do not have a clutch pedal. When the gear is shifted into the driving position, the clutch is already in a connected state. At this point, without the resistance from the brakes, the car will naturally move forward slowly. An automatic transmission, as the name suggests, does not require manual gear shifting while driving. The control system of the automatic transmission automatically selects the appropriate gear based on the engine speed and load, replacing the driver's subjective judgment and gear-shifting operations. The advantage of an automatic transmission over a manual transmission is that it is easier to drive. Additionally, automatic transmissions include continuously variable transmissions (CVT), electronic paddle shifters, and electronic gear lever transmissions. Currently, there are three types of vehicle transmissions: manual transmission, automatic transmission, and semi-automatic transmission.
I've been driving automatic transmissions for over a decade. When in D gear without pressing the accelerator, the car will indeed creep forward slowly, which is technically called 'creep mode'. The principle is that the transmission fluid pushes the turbine to generate power transmission, equivalent to the half-clutch state in manual transmissions. On flat roads, it's about 5-10 km/h, similar to walking speed. However, you need to be careful on slopes - the car will roll backward when going uphill unless you brake, while it'll accelerate when going downhill. Once when queuing in an underground garage, keeping in D gear without acceleration made following the car ahead effortless. But on steep slopes or when heavily loaded, if the engine lacks sufficient power, it may shake or even stall. In such cases, you still need to gently press the accelerator to provide some power.
Last week, a friend who just got their driver's license asked me about this. Simply put, most automatic cars will creep forward when in D gear, as if being gently pushed. However, for new energy vehicles like Tesla with one-pedal driving mode, or some cars equipped with Auto Hold function, they won't move without pressing the accelerator. Older cars are especially noticeable on slopes—they roll faster when the front is pointing downhill and may even stop and shudder when pointing uphill. Once, when driving my sister's old Camry out of an underground garage, it rolled backward in D gear without pressing the gas, which was terrifying. Actually, this is the torque converter at work, with transmission fluid pushing the car forward. But if the creeping suddenly stops, it's likely time to change the transmission fluid or there's a leak somewhere.
I've seen too many customers ask this question during repairs. The key is the transmission condition: normally, putting it in D gear is like releasing the handbrake on a bicycle rolling down a gentle slope. But during cold starts, there might be a slight delay before response when the transmission fluid hasn't warmed up. On slopes steeper than 5 degrees, FWD cars tend to roll backward while RWD cars may creep forward. It's more complicated with EVs - some don't activate the motor at all in D gear. Once had a BMW that wouldn't move in D gear, turned out the brake light switch was stuck so the ECU thought brakes were applied. Modern cars even have hill-start assist that holds the car for 2 seconds without throttle to prevent rolling.
