I'm not saying it doesn't happen, but shouldn't it be every time you get hit by a vehicle? The amount of damage taken should be different for each vehicle, ie, a bigger vehicle should be more likely to kill/seriously injure than say a atv. I have run people over with my tire running directly over their body and it didn't kill them. Or even hurt them.

I also had this problem today. I was playing a MP mission "wasteland" and I swam out to the island to the far north, and also to the island to the north-east, I was in as a medic, and I did not have a wetsuit nor a rebreather. I managed to survive both of the swims, but even while on the surface of the water I was drowning. I was able to get air after repeatedly diving then resurfacing, after a few tries I would usually breaks the surface and get some air.

I had this happen to me today while playing MP mission "wasteland" I changed weapons and I could see the new one, but my squad-mates saw my old weapon. I was a medic, not a diver.