Final answer:
In ideal driving conditions, the rule of thumb regarding following distance is to use the '3-second rule,' which helps ensure a safe following distance from the car ahead to allow for adequate reaction time. This distance should be increased in less than ideal conditions or when driving larger vehicles.
Step-by-step explanation:
In ideal driving conditions, the rule of thumb regarding the following distance suggested is the '3-second rule.' This means that when following another vehicle, you should remain at least three seconds behind the vehicle in front of you. To estimate this distance, when the rear of the vehicle ahead passes a stationary object, begin counting seconds ('one-thousand-one, one-thousand-two, one-thousand-three'). If you pass the same stationary object before you finish counting, you are following too closely and should increase your distance. This rule of thumb can help allow for adequate time to react and stop safely if the car in front brakes suddenly.
However, keep in mind that different driving conditions and speeds will require different following distances. For instance, the rule changes to a 4-second or more following distance when conditions are less than ideal, such as in bad weather or when driving a larger vehicle. Additionally, it's important to consider that the stopping distance will increase with speed, and the friction between the tires and the road surface can also affect the distance needed to stop safely.