Can you shift from D to R while the car is still moving? Or does the vehicle have to be stationary before you do this and vice-versa?
Conventional wisdom tells us that the latter statement is true.
However, automatic and direct shift transmissions actually allow selecting reverse from drive or vice-versa at very low speeds, such as during parking manoeuvres.
YES, IT’S POSSIBLE!
But when doing so, make sure your right foot is off the accelerator. In fact, selecting R or D when the engine is revving, even if the vehicle is stationary, is damaging to the transmission.
Shifting the transmission lever from D to R or even N to D thus requires the engine to be at or near idling speed.
Shifting to P is different. In P or Park mode, the transmission engages a lever into a toothed wheel. In P, a car cannot be pushed, nor will it roll down a slope.
Because of this mechanism, shifting to P when the car is still creeping – no matter how slowly – imposes stress on the toothed wheel and the lever.
For the same reason, it is best to engage the parking brake before shifting to P on a slope, no matter how gentle it is.
Most modern transmissions incorporate a safety control that prevents deliberate or inadvertent selection of P when the car is moving above a certain speed.
However, it is still best to shift to P only when the vehicle is at a complete standstill.