1. Me and a friend were taking tires off a truck and it shifted sideways and killed him and if you don't believe me on that I have a video clip of it. 2. Me and a friend just fixed up a ogla24 and we dove for about 5 minuets and the engine broke down so we went to go look for a pipe wrench to fix the engine and 2-5 minuets I go back to the car to notice it disappeared and I didn't hear any footsteps or the car starting.

Thank you for your time and I hope someone can find a reason for that to happen

The second instance is most likely normal. Not sure what caused the engine to be ruined (over revved the engine or drove without enough water in the radiator?) but once a vehicle's engine is ruined and you leave the area, it disappears. Even if it has items in the trunk. Not a great feature but I believe it is intended to work that way.