What is the actual speed when the car speedometer shows 100?
4 Answers
When the dashboard displays a speed of 100 kilometers per hour, the actual speed may be approximately 97 kilometers per hour. The so-called positive error means that the measured value is never less than the actual value, that is, the speedometer reading can be equal to or greater than the actual value, but it must never be less than the actual value. Here is some additional information: Speedometer principle: The speedometer signal comes from a sensor. In some manual transmission vehicles, the speed sensor is located on the output shaft of the transmission, while in automatic transmission vehicles, the speed sensor comes from the wheel speed sensor of the ABS system. The sensor can measure the rotational frequency of the object being measured. For example, the wheel speed sensor can measure the rotational frequency of the wheel, and then the wheel speed can be calculated based on hardware parameters and time. Knowing the speed and combining it with the wheel diameter allows the vehicle speed to be calculated.
I frequently test drive different car models and have noticed that the speedometer always shows a slightly higher speed than the actual speed. After multiple tests with a GPS device, when the display shows 100 km/h, the actual speed is usually between 97 and 98 km/h. This discrepancy is determined by regulations, as manufacturers intentionally set it higher to prevent drivers from speeding. The difference is minimal across different car brands, such as Japanese and European vehicles. Tire wear or changes in air pressure can also affect the reading, but the impact is negligible. It's recommended to verify with GPS in safe road conditions, avoiding distractions while driving. Understanding this can make long-distance driving more reassuring and help avoid speeding tickets. The key is to focus more on road conditions rather than relying solely on the dashboard numbers.
When driving my daily commuter car, I checked with a mobile GPS app and found that while the speedometer shows 100 km/h, the actual speed is only 96 or 97 km/h. This is a normal phenomenon, as manufacturers design it with safety in mind to prevent unintentional speeding. After replacing new tires, the reading may adjust slightly, but the change is minimal. I rarely pay attention to this detail while driving, and I suggest you don't focus too much on the numbers either. The key is to obey speed limits and stay alert. The actual speed difference is generally small, so there's no need to worry about handling issues. GPS checks should be done when parked—never distract yourself while driving. Safety always comes first.
After years of driving, I've noticed that the speedometer reads higher than the actual speed. When it shows 100, the real speed is about 95 to 97 km/h, which can be verified by GPS. This is part of a safety design to avoid speeding tickets or accidents. Don't test GPS while driving—it's too dangerous. Simply put, this is a good thing.
