You're not going to get a settlement. The navigation system has operated that way since Lexus started selling navigation systems in 1998, and plenty of other car manufacturers (most) have navigation that has blocked-out destination input when driving. Its a situation of "caveat emptor", when purchasing a $40,000 vehicle if the technology of the navigation system is of importance to you, a thorough test drive and use of the system would have provided you with plenty of information.
As for the update, version 9.0 will come out in September or October, I would wait for that. 8.1 is an upgrade from your car (which has 6.1, the system is always a year behind the year of the car).