Scott Dixon led his three Chip Ganassi Racing team-mates in a 1-2-3-4 at Sebring in the final IndyCar test of the off-season.
Sebring times traditionally mean little, especially with most teams being cautious in revealing when they were running a qualifying lap simulation.
But Dixon's 51.13-second lap time on Tuesday and Ganassi's monopoly of the leading positions suggests good progress for the team as it adjusts to the Honda aerokit, having swapped from Chevrolet over the winter.
Charlie Kimball, Max Chilton and Tony Kanaan were next up behind Dixon.
Will Power narrowly edged his reigning champion Penske team-mate Simon Pagenaud for fifth, with Helio Castroneves turning 86 laps, the most of anyone, in seventh.
Castroneves' newest team-mate Josef Newgarden was feeling unwell and could only complete 18 laps, but still placed eighth.
Ed Jones lost over two hours of track time while the Dale Coyne Racing team searched for an electrical gremlin, and was not accompanied by his team-mate, as Sebastien Bourdais had completed a test day earlier in the month.
Mikhail Aleshin, in his first road course experience of an IndyCar since last year's season finale at Sonoma, did an impressive job to draw within 0.03s of Schmidt Peterson team-mate James Hinchcliffe as they took 11th and 12th behind AJ Foyt pair Carlos Munoz and Conor Daly.
Andretti Autosport-Honda will run on Wednesday instead, while SPM stays on to test sportscar racer Pipo Derani and AutoGP champion Luis Michael Dorrbecker.
SEBRING TEST TIMES:
Pos Driver Team/Car Time Gap 1. Scott Dixon Ganassi Dallara-Honda 51.13s 2. Charlie Kimball Ganassi Dallara-Honda 51.42s +0.29s 3. Max Chilton Ganassi Dallara-Honda 51.56s +0.43s 4. Tony Kanaan Ganassi Dallara-Honda 51.75s +0.62s 5. Will Power Penske Dallara-Chevy 51.75s +0.62s 6. Simon Pagenaud Penske Dallara-Chevy 51.77s +0.64s 7. Helio Castroneves Penske Dallara-Chevy 51.79s +0.66s 8. Josef Newgarden Penske Dallara-Chevy 51.93s +0.80s 9. Carlos Munoz Foyt Dallara-Chevy 51.97s +0.84s 10. Conor Daly Foyt Dallara-Chevy 51.99s +0.86s 11. James Hinchcliffe Schmidt Dallara-Honda 52.01s +0.88s 12. Mikhail Aleshin Schmidt Dallara-Honda 52.04s +0.91s 13. Spencer Pigot Carpenter Dallara-Chevy 52.07s +0.94s 14. Graham Rahal Rahal Dallara-Honda 52.13s +1.00s 15. JR Hildebrand Carpenter Dallara-Chevy 52.28s +1.15s 16. Ed Jones Coyne Dallara-Honda 52.36s +1.23s