Rahal's margin of victory was 6.14 seconds.
In fact, Rahal's time (1:13.810) topped his former track record time of 1:13.968, as did James Hinchcliffe (1:13.826), who will start fifth.
Sato covered the 2.36-mile road course on Belle Isle in 1 minute, 13.6732 seconds at 115.434 miles per hour in his Andretti Autosport Honda.
Rahal ended an eight-year pole drought earlier in the day before retaining his lead at the start despite coming under pressure from Penske's Helio Castroneves, with the Brazilian eager to pick up his first victory in three years.
"It's a bomb waiting to go off and unfortunately, it did", Rahal said. He also became the first driver to win a doubleheader weekend since Scott Dixon at Toronto in 2013.
"These are the days that definitely help championships, when you've got to strive to get the most out of it, and I think we did a good job of that today". He won the pole earlier in the day with his Honda-powered vehicle and led a career-high 55 laps of the 70-lap race. You'll also hear from race fans Tom Okalski and Corey DeCoteau from Carsonville, MI; Zach Schubert from Fort Wayne, IN; and Tony Mocadlo from Albuquerque, NM. I think I was favoring a lot of things, but just so proud of the whole Camping World crew.
Will Power and Scott Dixon will start P7 and P8 respectively, with Power forced to take to the escape road at Turn 7 during the final moments of the second segment. "To be able to get off the (Firestone alternate) reds after the spin in the first turn there played to our advantage". It put us up where we belonged and I think we showed that the No. 5 Arrow vehicle had a lot of pace.
Takuma Sato begins the celebration on pit lane after winning the pole position for Race 2 of the 2017 Chevrolet Detroit Grand Prix.
Graham Rahal races during the IndyCar Detroit Grand Prix auto race on Belle Isle, Sunday, June 4, 2017, in Detroit.
The season's only doubleheader will conclude Sunday on Belle Isle.
"My auto was like a rocket out there", Sato told Brad Galli on pit lane shortly after qualifying. It's absolutely team credit.
"It means a lot to me and I'm very happy", said Sato of his qualifying run.
The prestigious L'Equipe magazine in France last week quoted Hamilton as saying of Fernando Alonso's IndyCar debut in the 101 Indianapolis 500, "I looked at the times and, frankly, for his first ever qualifying, for Fernando to be fifth - what does that say about Indy?"