"The controller of the vehicle is responsible for the speeding ticket, in case of an autonomous car it is the software which was written by the car manufacturer so they would have to be responsible as they are the only ones who can change behavior of the car and would be keen to not exceed speed limits..this is the point of fines."
And the insurers are insisting that all updates must be applied immediately and the user must not under any circumstances change the cars programming on penalty of voiding the insurance cover. So the passenger not only has no control over the cars choice of speed but will void their insurance if they do anything to change its behaviour.
Biting the hand that feeds IT
