Speed signal

Hi again,

I think i found the speed signal in my MB Viano (on comfort CAN)
The calculation into km/h is a bit strange:
(2 byte value / 16) - 1 under 30 km/h
(2 byte value / 16) - 3 above 30km/h

Although this seems to be correct from 10 up to 140 km/h, i think it's a bit strange that it needs to be calculated this way.

Can anyone shed some light or confirm/correct anything?

Thanks in advance and kind regards,
Marc