"I'm super excited for everybody involved," Bowyer said. "To switch teams like I did was a huge risk and a chance for me, and it was a chance to showcase my talents."
Tony Stewart passed Busch on the final lap to claim second, and Busch wound up third. "Got it by default there, to a certain degree," said Stewart, who was second for the second consecutive week.
Brian Vickers was fourth for MWR, followed by Hendrick Motorsports teammates Jimmie Johnson and Jeff Gordon.
There were only two cautions - the fewest in track history for the Sprint Cup Series.
Ferrari wins European GP
Fernando Alonso of Ferrari won an incident-filled European Grand Prix in Valencia, Spain, on Sunday to become the first driver to win two races this season, while Michael Schumacher earned a first podium finish since his comeback by coming in third.
Alonso jousted his way up from 11th on the starting grid to claim an emotional victory for the Spaniard in front of his home fans after pole sitter Sebastian Vettel's Red Bull stalled on the track midway through the race.
Kimi Raikkonen of Lotus finished second, while Schumacher sneaked onto the podium after Lewis Hamilton and Pastor Maldonado crashed on the penultimate lap as they fought for third place.
Wild IndyCar race in Iowa
Ryan Hunter-Reay passed Scott Dixon with 12 laps to go and held on to win for the second straight week in a wild IndyCar Series race that ended under caution Saturday night in Newton, Iowa.
The winner last week at the Milwaukee Mile, Hunter-Reay moved to second in the season standings with his seventh career IndyCar victory - the most among active U.S. drivers. Teammate Marco Andretti was second, followed by Tony Kanaan and Dixon.
It was only fitting Hunter-Reay would win under caution, because 10 of the 25 cars failed to finish.
Pole sitter Dario Franchitti was knocked out after his engine blew before the green flag dropped. Points leader Will Power was bounced just 68 laps in after E.J. Viso hit him from behind.