Muñoz, a regular in the Indy Lights development series with Andretti Autosport, had never made a pit stop in competition before the race and had little practice but learned quickly
"The first two pit stops, the one or two pit stops, was not that great," he said. "A lot of people overtook me. I went one-by-one back to the front. The last two pit stops, the guys and me, we did a great job not to lose any position."
Muñoz sat third behind champions Ryan Hunter-Reay and Tony Kanaan for the final restart with three laps to go. At the green, Kanaan went to the inside of Hunter-Reay, and Muñoz got around to the outside before Dario Franchitti's crash brought out the caution that ended the racing.
Muñoz aims to be in the IndyCar Series full time next year but is committed to Indy Lights for this season and wasn't sure if his finish would persuade owner Michael Andretti to add races to his schedule.
"It's up to him," Muñoz said with a smile. "I'm asking you guys to press what you think about it."
Stuck on three
Of the two drivers in position to join the elite four-time winners' club, at least Helio Castroneves had a chance. Castroneves hung around in the second five for much of the day, led a lap and finished sixth.
"[The car] was running smooth like a Swiss watch," Castroneves said. "It was very nice.
"I was just having issues with the [engine's rev] limiter. I was trying to pass a lot of people, but unfortunately it was hitting the limiter. That was one of those things.
"When you don't win you have to look at the positive side, and that is the championship."
Franchitti, the defending winner, was not competitive and crashed just after the final restart.
"Sums up our day," said Franchitti, who was credited with 23rd. "Our car was never really good all day. We couldn't make anything happen."