What is the purpose of the dotted line on the rearview mirror?
2 Answers
The dotted line on the rearview mirror is primarily used to observe situations at a farther distance on the side of the vehicle. Inside the dotted line, the curvature radius is larger, allowing observation of closer areas on the side of the vehicle. The combination of these two curvatures helps minimize blind spots in the rearview mirror. The small area of the dual-curvature rearview mirror also features a small indicator, which serves as a "side blind spot warning system." When there is a potential collision risk on the side of the vehicle, this indicator will flash to alert the driver. If the body of the following vehicle has entered the danger zone to the left of the dotted line on the rearview mirror, it indicates that the following vehicle is very close to your car, and you should not change lanes at this time. If the left side of the following vehicle's body is close to the boundary between the safe zone and the danger zone, you should be extra cautious, but signaling and turning at this point is still safe. If the following vehicle is in the safe zone, located in the center of the rearview mirror, it means the distance between your car and the following vehicle is about 15-20 meters, and you can safely perform turning maneuvers. Functions of the dotted rearview mirror: The rearview mirror with a dotted line is called a dual-curvature rearview mirror. It is divided into two main sections by the dotted line. The dotted line is located on the outer 1/3 of the mirror, while the inner section is the normal reflection zone, also known as the standard rearview mirror area. This area provides a nearly 1:1 reflection with minimal distortion. The outer section has a higher curvature, offering a wider field of view, which helps drivers better adjust their vehicle positioning. For example, during reversing, the wider curvature allows for a broader view of the reversing area. The entire dual-curvature rearview mirror acts like a small convex mirror, providing the driver with a wider field of vision. Since dual-curvature rearview mirrors are generally more compact, they help reduce wind resistance and improve fuel efficiency. Additionally, the warning system on these mirrors alerts the driver when there is a potential hazard on the side of the moving vehicle, prompting the driver to take evasive action. Most vehicles also come equipped with a rearview mirror heating function. In special weather conditions, activating this feature prevents fogging and ensures clear visibility. During heavy rain, applying a rain repellent to the rearview mirror can create a thin film on the surface, allowing water droplets to slide off quickly. This repellent can also be used on the windshield. It's important to avoid scratching the rearview mirror, as its plastic housing is difficult to repaint. When parking on the roadside, folding the rearview mirrors is recommended.
After driving for so many years, I find the dotted line on the rearview mirror quite practical, mainly designed to address blind spots. There are often invisible areas on the side of the vehicle, especially when changing lanes, which can be dangerous. The dotted line divides the mirror into two parts—the middle is a flat surface, while the outer section is a convex curved area, expanding the field of vision and helping you detect nearby vehicle movements while driving. For instance, during highway overtaking or turning at intersections, paying attention to the area divided by the dotted line allows you to spot potential risks early, reducing the chance of side-swipe accidents. It’s also important to clean the mirror regularly to prevent dust from covering the line—this is a small tip to ensure safety first. Combining it with turn signals in daily driving makes managing your field of vision even more effortless.
