No need for scenario for flipping, I know couple of them. Some just need car/surface adjustments. I still think that some flipping will be ok if the player is doing dangerous things, but yeah, now it sometimes flips for stupid reasons.
As for not moving after respawn, I really don't know how to reproduce that, although I think I saw it once. I suspect it's a glitch in the automatic-handbrake feature I've implemented to prevent it rolling while the player isn't controlling it, but it makes no sense from the code point of view, it literally turns it off each frame while the player is inside, and only turns it on when player exits the car. So might be something else entirely.