GPS Speedometer Premium_

Vehicle speedometers are typically designed to slightly overestimate speed as a safety measure and to comply with regulations that prohibit them from underreporting. This ensures drivers are not unintentionally speeding. In contrast, GPS devices calculate speed based on satellite data, offering a more precise and unbiased measurement. Variations can also result from factors like tire size, pressure, or wear affecting the vehicle's calibration.

GPS Speedometer Premium relies solely on the GPS sensor to provide accurate speed readings. Other apps may show your location using Wi-Fi or mobile networks, which are helpful for faster location initialization and indoor positioning — especially when GPS signals are blocked by ceilings or buildings. However, this network-based data lacks the precision needed to calculate speed accurately. To ensure reliable results, speed is only displayed when a strong GPS signal is available. More information is available at https://www.gps.gov/systems/gps/performance/accuracy/

More information is available at https://www.gps.gov/systems/gps/performance/accuracy/

GPS updates your location roughly every one second. A current location alone is not sufficient for measuring the speed. However, by using the formula:
speed = distance / time
Distance: The GPS calculates the distance between the current location (newest position) and the previous location (from 1 second ago)
Time: The time interval between these two location updates is usually 1 second, but can occasionally take longer if GPS signal is lost, which is taken into account
it's possible to calculate it. This means the speed displayed is not the instantaneous speed at the exact moment but rather the average speed over the previous second. Additionally, the GPS signal must travel between satellites and the device, which increases the delay even further.

Also please note that enabling Smoother speed changes in the Advanced section adds further delay.