Olga
After exiting the Olga and walking out of sight of the vehicle, on return the car has visually disappeared. It is however still there, as can be evidenced by trying to walk through the area where the car was parked. To get access to the car, I have to log and relog. The Olga then reappears.

Ada
after exiting the ada, the car disappears, then rises through the ground in that spot.
Unfortunately I do not have pictures or video of the ada