One data point I've noticed is that when a line of cars is at a stop light on a downward hill - when the light turns green, the traffic starts moving quicker th

One data point I've noticed is that when a line of cars is at a stop light on a downward hill - when the light turns green, the traffic starts moving quicker than on the same scenario on flat land or uphill. When getting off the brake the cars are already rolling a little bit before the move to the accelerator pedal and the effect is compounding. This shows that the small latencies do add up.