Question: Cover

[Warmonger]

Do knocked out vehicles provide cover? If they do, how does it relate to other cover? That is, given a choice of a clear hex with a knocked out vehicle and a hex with trees, which one would provide better cover?

Along the same line, would an infantry unit in a hex with a friendly tank be better off cover wise than by itself?

[Imp]

As far as I know its the smoke generated by the wreck that gives cover so yes wrecks provide cover.
Tank question is a strange one units are never a terrain feature as covered when you asked about bunkers so dont provide cover. Also as already covered in one of your posts if the tank is destroyed they will likely take a big morale hit.
Then there is the obvious stuff
The unit that entered last spent an extra MP to do so, so easier to see & it sees worse & has possibly lost shots.
Tanks attract fire & a unit stacked with it is suscepible to splash fire as suppresion or even if unlucky being hit by a near miss, as a player thats one juicy target.
At range also lets me suppress the infantry unit I could not see by firing at the tank perhaps to the point where I can see him.
So tanks & infantry in same hex is a only if absolutly have to move

[void1984]

On the other hand in tight environment - lots of smoke, city streets, wood etc. I sometimes have an infantry on the same hex as a tank to protect him from hidden assaulters.