How to Judge the Distance of the Rear Car by Looking at the Rearview Mirror?
4 Answers
Here are the methods to judge the distance of the rear car by looking at the rearview mirror: 1. The closer the rear car is to you, the less area of the rear car the driver can see, and it will be closer to the outer side of the rearview mirror; 2. The farther the rear car is from you, the more complete the area of the rear car the driver can see, and it will be closer to the inner side of the rearview mirror. There are four specific methods to judge the distance using the left rearview mirror: 1. First, take the center of the left rearview mirror as the reference line; 2. When the body of the rear car is on the left side of the reference line and cannot be fully seen, the distance is approximately 5 meters; 3. When the rear car is on the left side of the reference line and can be fully seen, the distance is approximately 10 meters; 4. When the car is on the left side of the reference line, and there is a width of one car between the car in the rearview mirror and the left edge of the rearview mirror, the distance is approximately 15 meters; 5. When there is a width of two cars between the car and the left edge of the rearview mirror, the distance is approximately 20 meters.
I've been in the long-haul transportation industry for over a decade and have mastered a set of rearview mirror techniques. The size and position of the following vehicle in the mirror are crucial: if it's only as big as a soybean, it means it's at least a hundred meters behind me; if it's basketball-sized and centered in the mirror, it's probably just ten or twenty meters away—that's when you should avoid changing lanes. I remember once on a mountain road with heavy fog and poor visibility, I relied on the mirror to judge distance and successfully avoided a rear-end collision. On highways, combining speed changes—if the following vehicle gradually appears larger, it means it's catching up quickly. In the city, before traffic lights, checking if the following vehicle's lights are fully visible helps you accurately estimate space, making driving safer and reducing accidents. Make it a habit to glance at the mirror for a few extra seconds, avoid impulsive decisions, and always prioritize safety.
When learning to drive, I was super nervous and always worried about misjudging distances when checking the rearview mirror. My instructor taught me this trick: the lower half of the mirror shows nearby cars, while the upper half displays distant ones. If a car behind looks as tiny as a sesame seed, it's still far away; if it appears as big as an apple, it's time to hold off on changing lanes. I started practicing in parking lots, asking a friend to slowly ride a bicycle toward me while I observed the mirror changes, gradually figuring out the pattern. Now when driving, I pay close attention to the position of the car behind—if it occupies more than one-third of the mirror, I definitely wait, ensuring there are no blind spots before making a move. This judgment is especially crucial on rainy days with poor visibility, helping avoid many potential scrapes. With more practice, it naturally becomes second nature over time.
The judgment method is actually not complicated: the rearview mirror's field of view is divided into a core area and an edge area. If the rear vehicle is in the core area and appears small, it indicates a short distance; if it's in the edge area and appears small, it suggests a longer distance. If the rear vehicle's size in the mirror is smaller than your fingernail, it's generally considered safe; if it's larger than your palm, caution is needed. During high-speed driving, observe the relative movement—if the vehicle is steadily decreasing in size, the distance is increasing. Many modern cars are equipped with blind-spot warning functions as an aid to improve accuracy. Always observe and think more while driving, and don't rely on a single point of judgment.
