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I will try and help. I am not sure this is a legal question, but here goes.
First, there is nothing to indicate that the 4:00 PM call is the exact arrival time. Secondly, there is nothing to suggest that an continuous 80 MPH is alleged. Further, it would seem unlikely that a van full of people would drive 6 hours non-stop with no refueling or lunch. Assuming 240 miles in six hours at a continuous speed, that's 40 MPH and that alone might get you a ticket on the highway.
I would figure out who was driving and send them the ticket.
I hope this helps.