Stefanik ran his first full Whelen Modified Tour season in 1987. He recorded his first championship in 1989, winning in seven of his 26 starts. He continued to be a major player in the 1990s, winning the 1991 series championship, finishing out of the top ten just once that season. After not running a complete schedule for a few years, Stefanik finished fifth in 1995 and won the 1997 and 1998 titles while simultaneously racing full-time and winning the championship those same years in the Busch North Series. Taking the 2000 season off to run full-time in the Camping World Truck Series, Stefanik won the championship his first two years back, not winning too many races but consistently placing in the top ten. Again pursuing other interests, Stefanik did not contend in 2003, 2004, or 2005 but won the 2006 season opener, completed every lap that season and only was out of first place for one week, winning the championship. Steadily trending downward from there, Stefanik's first full winless season came in 2010. He won his last race at Bristol Motor Speedway in 2013, and started his last race in 2014. In 2013, Stefanik competed in the inaugural UNOH Battle at the Beach at Daytona International Speedway. On the final lap, he was leading until he was turned by Eric Goodale; he finished 13th in the race. Afterwards, when Speed reporter Ray Dunlap arrived to interview him, Stefanik angrily stated he is "that freaking pissed. This is just bullshit." The interview was subsequently aired on The Jay Leno Show.
K&N Pro Series East
Stefanik won in only his third start, which came in 1991. He ran his first full season in 1993 while racing Modifieds and won the 1997 and 1998 championships, pocketing over $100,000 for each season. In doing so, he became the first driver to win two NASCAR championships in consecutive years; Lee Petty is the only other person to have won two championships in one year. Stefanik raced full seasons in 2003, 2004 and 2005 while stepping away from Modifieds, but did not have the same amount of success.
Craftsman Truck Series
Stefanik moved up to the Craftsman Truck Series, racing for Phelon Motorsports and finishing in the top ten nine times during 1999, achieving Rookie of the Year honors.
Halls of Fame
Stefanik was elected to the New England Auto Racers Hall of Fame in his first year of eligibility. He was inducted Nov. 11, 2018 by writer Mark "Bones" Bourcier. In 2013, Michael accepted his late brother Bob's induction. Bob and Michael are the fifth pair of brothers enshrined in the NEAR Hall. Stefanik was first nominated to the NASCAR Hall of Fame in 2015, and was elected to the Hall in 2020.
Death
According to Connecticut State Police, on the afternoon of September 15, 2019, Stefanik took off in a friend's Aero-Works Aerolite 103 from Riconn Airport, and was headed back when it experienced mechanical problems causing it to lose power and crash in a wooded area in Sterling, Connecticut. He was airlifted to Rhode Island Hospital, where he died from his injuries.
