Defending Sprint Cup champion Tony Stewart caused the first accident of Speedweeks.
Stewart, who did little wrong in last year's season finale and clinched his third NASCAR title, rear-ended Kurt Busch during practice Friday for the exhibition Budweiser Shootout.
Stewart turned Busch's No. 51 Chevrolet sideways, collecting four others.
Penske Racing teammates Brad Keselowski and AJ Allmendinger, as well as Kyle Busch and Jeff Gordon, also were involved in the six-car accident about 45 minutes into the first practice session.
"I was pushing the 51 car and he had to move a little bit, but I'm still the one pushing so I'm responsible for it," said Stewart, who was transported to the infield care center, treated and released.
The cars of Stewart, Kurt Busch, Kyle Busch, Keselowski and Allmendinger sustained significant damage. Stewart's crew decided to fix his car. The other four teams switched to backup cars.
Gordon's car sustained minor damage.
The Budweiser Shootout, a non-points race, kicks off the 2012 season Saturday night. It's considered a warm-up event for the season-opening Daytona 500 on Feb. 26, the series' premier event.
"It's the first time that we get back on the track and everybody is aggressive, learning what the limits are," Keselowski said. "Sometimes you get caught up in that. ... It's better to do it now than next Sunday. So hopefully we'll learn something from it and be good to go."