The 2.38-mile course in Birmingham, AL, saw all four Chip Ganassi Racing-Honda drivers in action.
According to unofficial times, six-time and reigning champion Scott Dixon led the test with a best lap of 65.774sec, 0.148sec faster than one of his new teammates, NTT IndyCar Series sophomore Alex Palou.
Dixon completed 85 laps, compared with 110 for Palou, and 120 for Marcus Ericsson, whose best effort was 0.440sec from Dixon’s.
Meanwhile Johnson turned a 67.131sec best in his 164 laps, 1.357sec behind Dixon.
“A great day in the books,” said Johnson in a little video on Twitter. “It’s my fifth day in the racecar, and a lot of things came to me.
“There was a lot of speed in the car, and I’m much closer on pace. I’m really sensing and feeling the car, and I’m really, really happy with the progress I’ve made.”
The seven-time NASCAR champion, who will compete in all 13 road and street courses on the 2021 IndyCar schedule, added: “The next time I’m in this car is here for the race weekend [the season-opener]. I wish I had a few more days in it, but that’s all we get.”
He also acknowledged his primary sponsor Carvana, commenting: “I’m really stoked to have the paint scheme on the car. It looks great on the track, and I can’t wait to come back here and race in a month’s time.”
The remaining tests on the IndyCar schedule will not involve Johnson. They include:
March 25 – four cars to validate package for the Indianapolis 500 on the Indianapolis Motor Speedway oval.
March 29 – Dale Coyne Racing-Honda and Carlin-Chevrolet test at Sebring International Raceway
March 31 – A.J. Foyt Racing-Chevrolet, Andretti Autosport-Honda, Arrow McLaren SP-Chevrolet, Ed Carpenter Racing-Chevrolet, Meyer Shank Racing-Honda, Rahal Letterman Lanigan Racing-Honda, and Team Penske-Chevrolet test at Texas Motor Speedway
April 8-9 – Open test on Indianapolis Motor Speedway oval.
– additional reporting from Trackside Online