CHARLOTTE — NASCAR overhauled its championship format Thursday, creating an elimination, winner-take-all system designed to reward "the most battle-tested" driver at the end of the season. An expanded 16-driver field will be whittled down to a final four through three rounds of eliminations. The remaining four drivers will go to the season finale with an equal chance to win the championship: The first of the four drivers to cross the finish line will be crowned Sprint Cup champion.