Most of my runs are right out the front door, but I've driven over an hour each way for a run in the mountains before. I've never even considered the environmental impacts of my driving. You guys drive to do other things, right? I don't see why running is any different. Heck, I drive 6 hours to Moab to rock climb and mountain bike occassionally. I could do that stuff within 30 minutes of my house, but I like to see other places.