After ending Wednesday as the fastest driver of the day, Andretti promptly asked for rain to wash out the next few days at Indianapolis Motor Speedway.
"When you're good, you always want it to rain and go right into the race instead of giving other guys time to catch up," he said.
Qualifying for the May 27 race begins Saturday and Andretti is anxious to get on with the show.
Andretti turned a lap at 227.053 mph around IMS in a strong showing for the American driver. Mario Andretti is the only member of the famed family to win "The Greatest Spectacle in Racing" and Marco Andretti has been desperately trying to add a victory to go alongside his grandfather's.
But going fast on Day 2 of practice ultimately means nothing, he admitted.
"This place is a humbling place. I mean, tomorrow you roll off with the same racecar, and could be 17th," Andretti said. "That's how the month goes. I prefer less practice."
Still, Andretti Autosport drivers have won three of the past four Indy 500s and Marco Andretti wants to be the one to keep the streak going.
"The car feels good," he said. "It's just circumstances have to work out really. I mean, this place picks the winners. I've had the best cars ever here and not been victorious for some reason."
Scott Dixon was second fastest at 226.329 and followed by defending race winner Takuma Sato. Robert Wickens was the next Honda on the board.
Charlie Kimball was fifth in a Chevrolet, and four more Chevy drivers followed him. Oriol Servia in a Honda rounded out the top 10.
Danica Patrick was 14th on the speed chart.
Both Andretti and Dixon said drivers are still trying to figure out what passing will be like on the speedway come race day. Dixon prefers momentum to be critical, while Andretti likes the idea of relying on track position.
"I prefer once you get to the front, have a good car, you should be able to stay there instead of being a sitting duck," Andretti said. "However, if you're third or back in line, it's going to be very tough. It's going to take discipline to wait for the guy to have a go and have a big wash-up, then you get him."
It was a busy on-track day for the 35 entries. James Hinchcliffe completed 129, and a total of 14 drivers went over 100 laps. In all, 3,349 laps were turned - the most on a practice day in at least five years.
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