I do almost always have a phone in the car but I tend to not carry a phone on my person unless I'm running. As noted it's because of my choice of running routes more than anything.
If I'm out in public or in a car I'm pretty connected just by being around other people or via personal identification and vehicle registration etc.
When I'm running I am just a random dude who would be a John Doe if I turned up when the snow melts.