Jay Howard, who hasn't competed in the series in four years, turned the day's fastest lap just after the track opened at noon.
Bourdais was one of 22 drivers who eclipsed 230 miles per hour in a tow. "My engineer loves to run and run, but with the limit yesterday, it helped us to be precise, to think clearly, and I liked it".
Alonso has completed four days of the opening week of practice for his first Indy 500, which he is contesting in a McLaren-Honda entry run by Andretti Autosport.
The Spanish McLaren Formula 1 driver was fourth quickest on Thursday with an average speed of 225.619mph.
Many within the sport also are suggesting Alonso could come back to Scuderia Ferrari, though he also has been linked to a return to Renault Sport F1 Team, with which he won his two world championships.
"Gil de Ferran, my coach, my mentor, told me the four laps in qualifying will be the most terrible you've ever done because the auto is very on the limit", said two-time F1 world champion Alonso, 35.
Dixon believes that both Honda and Chevrolet are engaging in a bit of sandbagging and won't show their true hands until "Fast Friday" when the manufacturers are allowed to dial in an extra 10kPa of turbocharger boost in an effort to raise qualifying speeds. Temperatures were up, speeds were down, and the tension that usually hangs over the Indianapolis Motor Speedway in the lead-up to Indy 500 qualifying weekend was generally less intense than usual. He's one of the drivers that is in the conversation for greatest living racing drivers. Qualifying gets underway Saturday but fans can get into the tack starting at 10 a.m. Friday. Coverage of Saturday's first day of qualifying will be available on WatchESPN from 11 a.m. -3 p.m. and on ABC from 4-6 p.m.
Saturday determines the order of running on "Pole Day", which is Sunday.
Roger Penske forever is linked with the late Mark Donohue, the driver who in 1972 delivered the first of team-owner Penske's record 16 Indianapolis 500 wins. "Here I am, a veteran driver, but it's all brand new to me".
"And that's why on May 28, on the biggest weekend in motor sports, I won't be with my Formula 1 team at the Monaco Grand Prix". "Although, it's what you expected, what we expected, to be honest".
"We'd like to leave an imprint ourselves and we do that with our arms around Mark in this particular situation". The anthem, the circuit, the racing - I'm very thankful to experience it.
Rahal added that the foundation will carry on Donohue's memory.