If the GPS lock is lost, have the car lock back onto the GPS signal quickly.
When you are leaving a ferry the navigation takes about 30 min to discover your new position. Given the navigation is a key function (supercharge stops, nav on autopilot, etc.) the car should discover the new position sooner (max 3-5 min) or there could be a “GPS reset” button in the navigation settings.
Moderator: This could be a problem with one specific car. We’ve never seen the issue with tunnels, which also lose GPS lock. Perhaps others can chime in and state the car S/X/3/Y and year.
(lightly edited by moderator)