Final answer:
The one-car length method for determining safe following distance requires one car length behind for every 10 mph of speed.
Step-by-step explanation:
When using the one-car length method to determine the following distance, you should be one car length behind the car in front of you for every 10 mph of speed. This is a simplified rule of thumb, ensuring that as your speed increases, so does your following distance, allowing more time for reaction and braking. For instance, if you are driving at 50 mph, you should maintain a following distance of at least 5 car lengths - each approximately 3.5 meters long - between your car and the car ahead.