Its NO BIG deal either way whether you wave or not. Some of us have enough confidence in our ability to drive that it's in no way a safety issue as some seem so adamant about . These are the ones who have a cheeseburger in one hand ans a cell phone in the other, God forbid they look away from the cell phone to glance at another vehicle coming straight at you.
I don't know who came up with the notion about waving across the "interstates" where you have a medium in between...what's the point in that. My waving is confined to a two lane rural road(one lane of traffic in each direction)....as I said, you can practically reach out and touch one another on such roads. The way some are thinking here is your standing up in the driver's seat frantically jumping up and down waving to get the other driver's attention where in reality, I simply raise my left arm momentarily glance at the other driver and continue down the road.... been driving a long time and have yet to be distracted enough for it to be an issue.
So, in retrospect, to wave or not to wave, that is the question? Do what makes you feel comfy!!! :B