The error between the speed display of the speedometer and the speed display of the navigation occurs in the process of driving the vehicle which makes most of the driver confused and also experience anxiety hence in this paper, by the car management law number 73 (2), tests were conducted with following procedures measured by standard speed tester to analyze the error clearly. The experiment was carried out by installing a car on a speed tester with a speed difference of 10km/h from 30 to 80km/h according to the manufacturer and the vehicle. The result was obtained by measuring differences of the speed display error between the speedometer and navigation when driving the car on the road at the same speed. With the standard speed gauge at 40km/h, error percentage of the speed tester and Morning was 15.9% (5.5km/h) and Sonata was 6.4% (2.4km/h). The error percentage between different car company models was 9.5%. With the standard speed gauge at 40km/h, the error percentage of speed displayed by navigation and Morning was 14.2% (5km/h) and Sonata was 5.3% (2.4m/h). The error percentage between different car company models was 9.6%(3km/h). It was shown that according to the standard safety and rules of the speedometer, the cars were manufactured considering the safety. The speed difference between the speed tester and the navigation was 1.7% (0.5km/h) for Morning, 0.6% (0.2km/h) and 1.1% (0.3km/h) for Trax.