While driving, can you shift from 'drive' to 'L' while the car is in motion, in order to coast to a stop quicker?
Hey there. In general, "yes", you can do this. Most automatic transmissions allow this, within limits of acceptable engine speed. But this will accelerate transmission internal clutch wear, with shock loads on the axles, CV joints, engine, and differential. Modern braking systems with ABS are already pretty-much optimal for maximum braking performance. I wouldn’t bother shifting from ’D’ to ’L’.