So in BeamNG, inside the files, all values are in a specific unit, time in seconds, RPM, PSI etc. But the speed is quite strange. As example, 100 km/h equal to 27.82005711 or about 27.8 [internal speed unit]. Just wanted to point it out if anyone needs this info for adjusting speedometer gauges, or adding the top speed value in the config info file.
BeamNG uses meters per second (m/s) as its internal speed unit, which is the scientifically accepted SI unit for velocity and speed. m/s * 3.6 = km/h. m/s * 2.23694 = mph.