Final answer:
To maintain a space cushion, keeping at least a 2-second following distance is recommended when driving at higher speeds.
Step-by-step explanation:
When driving from 46 to 70 mph on Virginia roads, to maintain a space cushion between you and the vehicle ahead of you, it is recommended that you keep at least a 2-second following distance. This is a safety measure that helps to ensure you have enough time to react and stop if the car in front of you brakes suddenly. Maintaining a constant speed can help in keeping a steady following distance, but it alone does not guarantee safety. Using high beams at night improves visibility but isn't directly related to maintaining a following distance. Sudden braking should be avoided as it can cause accidents, especially at high speeds. Instead, make sure to adjust your speed and following distance according to road conditions and traffic regulations.