He'd have been better off staying with his family. Hindsight is 20/20. Prayers that he is found soon and safe.
He probably thought that they would never be found, so he set off on foot. It doesn't sound good for him I'm afraid. The best thing for them to do, IMHO, would have been to do things to attract attention to the car, from the air. I dunno, I watch too much of "Man vs Wild", "I Shouldn't be Alive", and that one with the Canadian guy, forgot its name..
This isn't the first story I've read where the people who stay behind get rescued, but the one who goes for help doesn't.
He was apparently wearing cotton blue jeans...
Bad news when we heard that he left the road for a creek bed.
Prayers for the family.