On January 10, 2017, he announced he was stepping away from NASCAR to pursue other opportunities. Carl realized his best days were behind him so he took to the ways of his idol, Brett Favre, to model wrangler jeans.
Fox Sports just posted an article saying its "to pursue interests outside of NASCAR".
I think several of the drivers don't like the corporate change in NASCAR over the past 5-6 years. Being a Tony fan, I know he hated it. Couple that with 36 race weekends out of 52 and its not surprising some of these guys are giving it up.