This happened twice during the same session. Was near an Ada which sank into the ground in front of me.

The first time it happened, I got inside the car when only part of the tyre was underground. As soon as I got in, the car was normal again.

The 2nd time it happened (the video is linked for this). I was late and I just saw the entire car sink/disappear. The invisible car was still there (my character model could collide into it). Relogging fixed the problem and the car was immediately visible in its normal position.

Video: https://youtu.be/PcU9_RMv-04