whatever you find works best. i usually go about 200 yards.

Do it all the time and the deer seem to hang around the truck

I believe location of stand determines distance to park. The surrounding vegetation works great as a cover, so parking close works in some cases.

I would think that where in the U.S. you hunt would make a difference.
Where I hunt in upstate NY,deer are use to hearing,seeing and smelling cars travel the roads all the time.So I park along side the road and start hunting as soon as I get in the woods.I've shot deer 30 yards from my truck.
I've never been out west but have watched alot of hunting shows,where they hunt in Wyoming,Montana,etc:The ground seems to be alot more open and they shoot alot farther than I have to.

I hunt public land and park anywhere from 7 to 3 miles from where I get up a tree. Use bike on non-vehicle roads.