Playing co-op with my husband yesterday I crashed while in the car after we had just came home with a car full of stuff. On logging back in both I and the car fell through the map. I rezzed elsewhere but there was no sign of the car. Hubby went back to an earlier save. The next time I crashed in a car he unloaded the car before I logged back in. We still lost the car. In total this happened 3 times yesterday.
In addition to this we found using a keybind to get out of the car caused a severe desync issue where my husband (who was hosting) couldn't even see me. This was happening often but hadn't happened previous to setting and using the keybind. After removing the keybind it didn't happen again