It happened to me just once but it sucks. I called my car which was parked in a safe place and it was demolished and almost destroyed but still it was possible to drive it. After re-load the car was totally fine. LOL
This happened a LOT with previous updates but over the last few has become less common. What I've seen is cars spawning perfectly fine, but without windows. But it's so infrequent I haven't bothered to track it down.
One thing I've found helps is to call another car, save/reload, the car you want should spawn fine and not have issues for a long while again.
Yup, happens regularly. Sometimes you can actually see it go straight trough some structure or clip trough hill that damages it. Seems to be more frequent in difficult terrain (sloped roads, roads intersecting on multiple levels, player away from road etc). Not a big problem though - it's easy to explode it an call again without wanted, and even if smashed up it still seems to have full health.