Every day I'm riding a 4 wheeler on the farm taking feed out, checking fences, etc. I don't know how many are the same deer that are just used to it, but the 4 wheeler spooks them a lot less than me walking. I know they can hear/see the atv way before I get to them but they don't bounce off until I'm in their comfort zone. If I'm walking, as soon as I'm spotted they are hauling azz.

I think the impact of an atv on deer is minimal. If you think it's affecting deer you're hunting then you're driving it to close to where you're going to hunt.