I heard two seconds, but three is even safer.
Also works for how long it takes to contaminate a dropped food item.
The technique used for determining the proper following distance is the "3- second" rule.
When following large trucks, maintain at least a minimum of a ______ second following distance.
a four second following distance. Get with the program! :)
Read your state's Driver's Manual. You will find that three seconds is rarely ever enough distance.
Maintain the same speed as the car in front. Pick an object to use as a reference like a road sign, and as the car in front passed the sign, start counting. If you pass the reference in 3 seconds or more, you are following at a safe distance.
Yes, using either the 2-second rule or the 3-second rule means that as your driving speed increases, you leave more distance between you and the car ahead of you.
The 3 second rule (sometimes it's a 2 second rule) refers to the spacing a vehicle should maintain when following another vehicle, regardless of speed. The theory is that the faster the vehicles are traveling, the greater the margin of safety (spacing or distance) between the vehicles will be.