How to Use Rearview Mirrors to Judge the Distance of the Following Vehicle?

[Kimberly]

When judging the distance of the following vehicle, we need to adjust the rearview mirrors. The adjustment is complete when the door handle of the following vehicle is at the middle height of the rearview mirror. When looking at the rearview mirror, it should be divided into "inner side" and "outer side". The half of the mirror closer to you is the "inner side", and the half farther away is the "outer side". If the following vehicle is closer, the visible area of the vehicle in the mirror will be smaller. Conversely, if the following vehicle is farther away, the visible area will be more complete and closer to the inner side of the rearview mirror. If you can only see the hood of the following vehicle through the interior rearview mirror but not the grille, the distance is approximately 3 meters. If the grille is visible, the distance is about 8 meters.

[CamilaMarie]

Well, I've found that the key to judging the distance of the following car lies in observing the size change of the vehicle in the rearview mirror, which requires developing some habits. From my daily driving experience: when you've just adjusted the rearview mirror to ensure you can see a small portion of your car's rear window, if the following car appears as tiny as an ant in the mirror, it's generally over 100 meters away; if it starts to occupy half the mirror, it's about 50 meters away; once it nearly fills the entire mirror, it means it's very close, possibly only 5 to 10 meters away, and changing lanes at this point is quite dangerous. I usually like to practice this on highways—when maintaining a constant speed, the gradual increase in the size of the following car helps estimate the closing distance. Combined with the three-second rule, if the following car rapidly grows in size within three seconds, you need to be extra cautious. Don't forget to check the side mirrors to eliminate blind spots and regularly clean the mirrors for clarity—these small details can make your judgment more accurate and ensure safer driving.

[ParkerRose]

When judging the distance of the vehicle behind, I primarily rely on visual cues from the rearview mirror: a shrinking car image indicates greater distance, while an enlarging one means it's getting closer. Specifically, if the outline of the following vehicle still faintly reveals distant objects like billboards or street trees, it's still far away; if only a small portion of its edge is visible, you can relax a bit. But when its front end becomes clearly visible and occupies the center of the mirror, the distance may have narrowed to within 20 meters – hard braking at this point could easily cause a collision. I always emphasize this when teaching friends to drive: in crowded urban traffic, observe the following vehicle's speed through the mirror and adjust your speed in sync with traffic light changes to avoid sudden stops. Keeping mirrors clean is crucial – blurred taillights after rain can impair judgment, so developing a habit of quick wipes before driving can significantly improve accuracy.

[VonJosiah]

When I first learned to drive, I relied entirely on the rearview mirror to judge the distance of the car behind me: the smaller the car appeared in the mirror, the safer it was; the larger it appeared, the more cautious I needed to be. For example, when stopping at a red light, if the car behind still looked small in the mirror, it meant it was far away. But once its headlights became noticeably larger in the mirror, it meant the car was approaching. I often practiced observing my neighbors' cars on the residential roads—at low speeds, changes in the outline of the car behind were easier to detect. Combined with a quick glance over my shoulder to confirm the distance, the mirror was the primary tool but not foolproof.