Scott Dixon was quickest again on the final day of the first major group test of the new DW12 IndyCar at Sebring on Friday.
Double champion Dixon left it until the very last lap of his afternoon's running to put in a 51.794-second lap and pull 0.229s clear of his Ganassi team-mate Dario Franchitti.
"We did the work on the car and as the sun went down a bit and the clouds came in, the track picked up some time," said Dixon. "We definitely worked to make the car better as well. I was good to do something for the lads at the end and it worked out."
The result was Ganassi's second one-two in as many days, although its habitual main rivals Penske and Andretti had both been out in the first group of the split test on Monday and Tuesday instead.
Rubens Barrichello was third again, both setting the pace among the Chevrolet-powered cars and comfortably beating KV team-mates EJ Viso and Tony Kanaan.
Foyt Racing's Mike Conway was fourth, but disappointed with the gap to the front.
"We need to go quicker because four tenths is massive around here," said Conway.
Graham Rahal (Ganassi), Takuma Sato (Rahal Letterman Lanigan) and JR Hildebrand (Panther) were next up, with reigning Indy Lights champion Josef Newgarden showing well in eighth for Sarah Fisher Hartman Racing.
Oriol Servia was fastest Lotus runner again for Dreyer & Reinbold, while four-time Champ Car champion Sebastien Bourdais had his first run with Dragon Racing as he took over team-mate Katherine Legge's car for a while.
Pos Driver Team/Car Time Gap
1. Scott Dixon Ganassi DW12-Honda 51.7938s
2. Dario Franchitti Ganassi DW12-Honda 52.0157s + 0.2219s
3. Rubens Barrichello KV DW12-Chevrolet 52.2242s + 0.4304s
4. Mike Conway Foyt DW12-Honda 52.2243s + 0.4305s
5. Graham Rahal Ganassi DW12-Honda 52.4692s + 0.6754s
6. Takuma Sato Rahal DW12-Honda 52.5541s + 0.7603s
7. JR Hildebrand Panther DW12-Chevrolet 52.6518s + 0.8580s
8. Josef Newgarden Fisher DW12-Honda 52.6551s + 0.8613s
9. Charlie Kimball Ganassi DW12-Honda 52.7328s + 0.9390s
10. EJ Viso KV DW12-Chevrolet 52.7951s + 1.0013s
11. Oriol Servia Dreyer & Reinbold DW12-Lotus 52.9178s + 1.1240s
12. Tony Kanaan KV DW12-Chevrolet 52.9195s + 1.1257s
13. Alex Tagliani BHA DW12-Lotus 53.1502s + 1.3564s
14. Sebastien Bourdais Dragon DW12-Lotus 53.2993s + 1.5055s
15. Ed Carpenter Carpenter DW12-Chevrolet 53.4764s + 1.6826s
16. Katherine Legge Dragon DW12-Lotus 53.8161s + 2.0223s