Wrong value in Summary Report
It simply means there's some issue with either distance or hours.
I had similar problem in cars with "smart/adaptive charging" with teltonika tracker. Ignition was detected when voltage > 13.3 V, which is not the case in newer cars. Try to disconnect smart charging connector, or set ignition source of your tracker to ignition+movement or so.
Traccar calculates average over time of "engine running", so my Ducato van was doing 420 km/h
In the report, the value of the average speed seems to be incorrect, since as observed, there are vehicles showing 2600 km/h. Version 6.9.1
Regards