Hi, Dont know whether the same rule of thumb applies internationally but here in Germany it states that the follow distance should be equal to half of the speed in kmh in meters. I thought about it and it doesnt seem to make any sense whatsoever. Ive heard people say it's because the braking distance increases with speed. Well apparently they forgot the braking distance of the one driving infront also increases. Infact thinking more abt it actually the exact oppsoite is true. It takes longer for a car to brake from say 200-150 kmh than from say 50-0 kmh. So the driver behind wld be much safer if he followed closer at a speed of 200 kmh. For now say the front brakes and in 2 secs reaches 170 kmh, the impact speed wld be 30 kmh. Whereas whilst following closely at speed of 50 kmh the same 2 secs with same braking power cld make the car stop compleetly and the impact be 50 kmh which is much worse. Are the lawmakers nuts here or is there another reason behind this "rule of thumb"? Thanks.