After some struggle with my base settings, I finally got reliable fix, but still the speed display is really all over the place!
I mean, top speed of my fergusson is 270km/h according to AoG
Also in field speeds the numbers are of by at least factor of pi!
I use the 10Hz rover config from Ardusimple for my f9p and it seemed to have those speed related messages enabled and I have f9p on usb.
So either there is something seriously wrong or I have to go drag racing local porche drivers
Thanx for your help!