When traveling behind another car, the safe following distance is generally recommended to be at least a three-second gap. This means if the car in front passes a fixed object, you should count at least "one-one-thousand, two-one- thousand, three-one-thousand" before your car reaches the same object to ensure a safe distance. This rule helps maintain enough time to react and stop safely to avoid collisions under normal conditions. The exact distance can vary depending on speed and conditions:

• At speeds below 35 mph, a two-second gap might be sufficient.
• Between 35 to 45 mph, a three-second gap is advised.
• For speeds from 46 to 70 mph, a four-second gap is safer.
• More distance may be required under poor weather, low visibility, or when driving near large vehicles.

This time-based rule adapts to the speed you are driving because it measures space as a function of time rather than a fixed physical distance, providing flexibility for different driving situations. In summary, keeping at least a three-second following distance is a common and effective guideline to ensure safety behind another vehicle on the road, adjusting it longer if conditions require.