A seat belt doesn’t care how far you lean, only how fast. Reach for the glovebox slowly and it pays out as much webbing as you like; lunge for it and it stops you after an inch. Inside the reel a small weighted lever rides on the spool, held in by a spring. Turned gently, it stays put. Spun fast, it flings outward and drops a pawl into a ratchet, and the belt is locked. Most belts also carry a little pendulum that swings when the whole car brakes hard, so either you or the car can trip it. It’s a strange kind of rule to be held by: you may go anywhere you like, provided you’re in no hurry to get there.