How to Determine the Distance from the Rearview Mirror to the Vehicle Behind?
3 Answers
When the rear vehicle appears on the left side of the left rearview mirror and the entire vehicle is visible, the distance between the rear vehicle and your own car may be only about 5 meters. If you notice that the body of the vehicle on the right has extended beyond the right side of the rearview mirror, the distance at this point may be around 5 meters.
As a long-time driver, I believe judging the distance of vehicles behind by looking at the rearview mirror is a matter of practice makes perfect. The key is to observe the size of the vehicle in the mirror: if the vehicle behind looks very small, like a tiny dot, it's definitely more than 20 meters away; if you can clearly see the details of the entire car, such as the license plate and taillights, it's probably between 15-20 meters; when the car occupies half the space in the mirror, the distance is about 10 meters; if the front or part of the car fills the mirror, it's very close, less than 5 meters, and you should avoid changing lanes at this time. Combine this with the side mirrors for assistance: if a car disappears from the center mirror but suddenly appears in the side mirror, it may already be in the blind spot. For safety, pay some attention to the mirrors while driving, but don't stare at them; a quick glance before changing lanes is sufficient. Judging distance becomes harder in poor light conditions, so slow down early in rain or fog and leave extra safety distance. Developing a habit of regularly cleaning your mirrors can reduce misjudgments.
I've only been driving for a little over a year. A simple method I learned as a beginner is to judge distance by the proportion of the car in the rearview mirror. My instructor taught me that if the entire body of the following car is clearly visible and the wheel outlines can be distinguished, the distance is generally about 15-20 meters; if only the car's hood or engine part is visible, it's roughly just over 10 meters; if only the license plate or headlights are showing, it means the car is very close, possibly within the dangerous range of less than 5 meters. I've practiced this on highways – at higher speeds, cars appear to shrink faster, making distance perception more ambiguous. For regular road practice, have a friend drive behind you while you estimate positions by checking the mirror – it's quite fun. Be careful not to let clutter block the mirrors, as judgment is more accurate in good light; at night, use dashboard lighting to enhance visibility. Always turn your head to check blind spots before changing lanes to avoid impulsive maneuvers. With accumulated experience, you'll naturally get the hang of it.