If you cannot see a car in your mirror but were aware of its approach, what should you do before changing lanes?

The best course of action when you cannot see a car in your mirror but know it is approaching is to check your blind spot. Vehicles can be in areas that are not visible using mirrors alone, especially in the blind spots located next to and behind your vehicle. Checking your blind spot involves turning your head to look over your shoulder to ensure that no vehicles are present in that area before making a lane change.

This step is crucial for safe lane changes, as it helps ensure that you are aware of any vehicles that may be in your blind spot, preventing potential accidents. Quick lane changes without a thorough check can lead to collisions, especially if there was an approaching vehicle that you could not see in your mirrors. Assuming the road is clear or signaling without confirming the surrounding area does not account for the presence of nearby vehicles and increases the risk of an accident.