There are tons of places with no cell coverage where I live in VA and WV. I'm quite certain you'll run into many places like that out west too. In VA we have entire counties with only 1 cell tower. I certainly wouldn't rely on cell phones for car to car communication.
FRS walkie talkies are what you want but you won't get more than 2 miles from them. CB's aren't going to go much further, certainly not 35 miles like someone stated. That might be possible with a full power radio, a big antenna, and nothing in between. You'll be using a handheld with a small rubber antenna inside a car. That equals poor range.
