I've seen a lot of people reporting this bug but nothing is done. It's just like the player list which they willingly removed. Duh . I dont understand WTF dayz developpers are doing and I'm afraid they don't either.
By the way, it's useless to report bugs because there has been no activity from the developpers since last wednesday.
And I read a comment from a guy saying they were taking a break for sometime. Not sure though

I think there is some kind of persistance. I had a fully working sedan that was still there AFTER a server restart. And then i crashed it and it just disappeared. *Pouf*. My guess is that working vehicles will remain on the server as long as you dont crash them. And not-working vehicles will respawn after an undetermined amount of time. In the exact same spot !

It's actually called a "lightning" but thunder flash is a good guess ^^
I played dayz a lot lately and i can tell you that you can see a lightning strike every 5 minutes. I think they just randomly appear in the sky since they are not linked to the weather's condition.

uhhh wtf ? How do we know which players are on the server then ? Like to check if we are on the same server as a friend. Jeez

So why can't we see the vehicle's health ???? Or some kind of indicator maybe, is it that hard to do ? If you want to make that game the most difficult and frustrating experience ever, i think you've reached your goal. Jeez