Tony Stewart still doesn't know when he'll be back in his car to begin his final NASCAR season.

And yes, the three-time Sprint Cup series champion says he's still done after this year.

Stewart defied his doctors' wishes with a cross-country flight to Nevada this week because he couldn't sit at home any longer.

Rest is necessary for healing from a back injury, but Stewart felt compelled to support his teammates and employees at Las Vegas Motor Speedway this weekend when NASCAR opens its three-race Southwest swing.

Stewart will have X-rays next week in North Carolina on his back, which was injured in a low-speed dirt buggy accident. He had surgery to stabilize his broken vertebra, but his doctors haven't examined his progress or allowed him to begin rehabilitation.