According to reports from USAC officials, Hmiel crashed during a qualifying run for the Sumar Classic 100 at the Terre Haute Action Track dirt oval in Indiana, 77 miles west of Indianapolis.
His car made contact with the barrier after rolling several times, suffering damage in the roll cage area.
Hmiel, son of Earnahard Ganassi Racing's Director of Competition Steve Hmiel, was transferred to the Methodist Hospital in Indianapolis with head injuries and is listed in critical condition in the intensive care unit.
The 30-year-old, who received a life-ban from NASCAR in 2006 after failing three separate substance abuse tests, was airlifted to Indianapolis Methodist Hospital where he was listed in critical condition with head injuries, according to USAC.
"We are very concerned about Shane and offer our resources and our support to his family during this time of healing," said USAC President/CEO Kevin Miller.
Hmiel has been rebuilding his career in sprint cars over the last three years following his sobriety and was voted USAC's most improved driver last season. He currently lies third in the Silver Crown standings behind Bud Kaeding and Levi Jones.
Shane is the son of Steve Hmiel, who is director of competition at Earnhardt Ganassi Racing.
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