"I'm super happy with how the day went," said Herta, 2018 Indy Lights runner-up. "We did some great things to the car and I'm very happy with how the boys got everything together in time for this test.

"Everyone did a fantastic job and there were no issues with the car; it was perfect. We kept chipping away and kept finding time. By the end of the day, we were quickest by quite a margin. I can't wait for tomorrow now."

Power's temporary – and previous – teammate Helio Castroneves in a fourth Penske, was allowed to halt his full-fuel load runs to jump up to third place, albeit 1sec off the ultimate lap from Herta.

Rookie Felix Rosenqvist outpaced Chip Ganassi Racing-Honda teammate by 0.0023sec to grab fourth spot, while Simon Pagenaud made it three Penskes in the top six.

Alexander Rossi was fastest of the Andretti Autosport-Hondas in seventh place, a couple of tenths faster than Graham Rahal who showed major improvement from Rahal Letterman Lanigan Racing’s form at the WeatherTech Raceway Laguna Seca test last Friday.

Dale Coyne Racing’s Santino Ferrucci did a fine job to slot into ninth ahead of Ed Carpenter Racing’s Spencer Pigot who, along with Rosenqvist turned the most laps of the session (38).

Marcus Ericsson and James Hinchcliffe were 11th and 12th for Arrow Schmidt Peterson Motorsports, ahead of Josef Newgarden in the fourth Penske entry.

Ryan Hunter-Reay, who had to have a tow-in early in the three-hour session, narrowly edged teammate Marco Andretti, while RC Enerson was 18th in the faster of the two Carlin-Chevys.

Ed Jones pipped former teammate Bourdais to ninth, while Kyle Kaiser’s Juncos Racing entry was 24th, 3.25sec off Herta’s pace after missing the morning session.

Tony Kanaan’s AJ Foyt Racing-Chevy lunched its gearbox, so he only completed six laps.

Testing times:

Pos.	No	Name	Time	Gap	Laps	Engine	Team
1	88	Colton Herta	1:46.626		22	Honda	Harding Steinbrenner Racing
2	12	Will Power	1:47.104	0.4786	28	Chevy	Team Penske
3	3	Helio Castroneves	1:47.695	1.0691	36	Chevy	Team Penske
4	10	Felix Rosenqvist	1:48.045	1.4193	38	Honda	Chip Ganassi Racing
5	9	Scott Dixon	1:48.047	1.4216	28	Honda	Chip Ganassi Racing
6	22	Simon Pagenaud	1:48.058	1.4324	33	Chevy	Team Penske
7	27	Alexander Rossi	1:48.122	1.4958	30	Honda	Andretti Autosport
8	15	Graham Rahal	1:48.341	1.7152	32	Honda	Rahal Letterman Lanigan Racing
9	19	Santino Ferrucci	1:48.385	1.7593	22	Honda	Dale Coyne Racing
10	21	Spencer Pigot	1:48.399	1.7729	38	Chevy	Ed Carpenter Racing
11	7	Marcus Ericsson	1:48.406	1.7799	28	Honda	Arrow Schmidt Peterson Motorsports
12	5	James Hinchcliffe	1:48.410	1.7843	28	Honda	Arrow Schmidt Peterson Motorsports
13	2	Josef Newgarden	1:48.421	1.7952	22	Chevy	Team Penske
14	26	Zach Veach	1:48.569	1.9435	26	Honda	Andretti Autosport
15	28	Ryan Hunter-Reay	1:48.710	2.0838	21	Honda	Andretti Autosport
16	98	Marco Andretti	1:48.714	2.0885	20	Honda	Andretti Herta Autosport
17	60	Jack Harvey	1:48.901	2.2757	27	Honda	Meyer Shank Racing
18	23	RC Enerson	1:48.996	2.3697	27	Chevy	Carlin
19	20	Ed Jones	1:49.208	2.5819	28	Chevy	Ed Carpenter Racing
20	18	Sebastien Bourdais	1:49.223	2.5973	30	Honda	Dale Coyne Racing
21	59	Max Chilton	1:49.266	2.6403	30	Chevy	Carlin
22	4	Matheus Leist	1:49.498	2.8717	17	Chevy	AJ Foyt Enterprises
23	30	Takuma Sato	1:49.524	2.8981	19	Honda	Rahal Letterman Lanigan Racing
24	32	Kyle Kaiser	1:49.875	3.2489	34	Chevy	Juncos Racing
25	14	Tony Kanaan	1:51.079	4.4533	6	Chevy	AJ Foyt Enterprises