By leaving room between their car and the one ahead of them, drivers can absorb a wave of braking in dense traffic conditions that would otherwise be amplified into a full-blown "phantom" traffic jam with no obvious cause. "Just keeping away," he says, can help traffic flow smoothly.
Some driving techniques make traffic behave like fluids: Compressible gasses (Car ahead of you slows - you slow some but progressively more as you get closer, Car beside you jogs left two feet, you jog one foot. etc.) Liquids (cars close up and hold constant distance) Crystals (at a traffic light or full stop, cars close up into a tight ordered array.) Condensation (similar near-constant spacing but not so ordered and flows (more easily), Chrystallization, Melting, Sublimation, Evaporation (when the obstruction clears and the first cars can speed up, then later ones, ...), laminar (smooth) flow, turbulent flow, shock waves, ...
Spacing out lets you behave more like a gas - or the first of the liquid behind a bubble - rather than a liquid or solid. When a sudden speed reduction throws a shock wave at you at several times the traffic speed, you can let the gas compress or the cavitation bubble shrink, diffusing the shock wave into an acoustic wave and avoding a collision with the car ahead. It also lets you even out the flow, remaining laminar rather than starting an eddy and going turbulent.