Milless joined Sarah Fisher Hartman Racing along with Newgarden at the end of 2011, and was his race engineer through the team’s various iterations – SFHR, CFH Racing (when it merged with Ed Carpenter Racing to form Carpenter Fisher Hartman) and finally back to Ed Carpenter Racing this season.

In 2015, Newgarden scored the first two wins of his IndyCar career at Barber Motorsports Park and Toronto, and this year dominated at the Iowa Speedway. However, with Newgarden moving to Team Penske, Milless has elected to join Andretti Autosport where he will engineer the #98 Andretti-Herta entry of Indy 500 winner Alexander Rossi. The former race engineer for this car, Tom German, has left the team.

Eric Bretzman, Scott Dixon’s former race engineer at Chip Ganassi Racing, who has spent the last two years overseeing Ganassi’s NASCAR team, has joined Andretti Autosport as technical director. Ray Gosselin will continue to engineer Ryan Hunter-Reay’s #28 car, with Nathan O’Rourke continuing with Marco Andretti.

Rob Edwards, team manager at Michael Andretti’s team, told Motorsport.com: “There had long been rumblings of Josef going to Team Penske, of course, and we weren’t sure initially whether those plans would also include Jeremy. Once we learned they wouldn’t, we saw there was an opportunity.

“We looked at the last two or three years, how Josef and Jeremy had grown together and saw some of those same opportunities with where Alexander is at now, with his first IndyCar season under his belt. We see a chance of Jeremy and Alexander to grow together over the next few years, so a great fit from that point of view.”

Asked if Milless’s apparently excellent handle on IndyCar setups with the Chevrolet aerokit would be transferrable to the Honda aerokit, as used by Andretti Autosport, Edwards said: “From what I know of Jeremy, he’s a good solid engineer and what impressed us was that with a relatively small amount of resource, he helped Ed’s team become a constant contender at pretty much every racetrack we go to.

“So his ability to work from engineering principles and work with Josef on how to apply it, those things really attracted us. Given there are fundamental differences in the car he worked with last year and what he’ll work with this year, that was less of a factor.”

Bretzman “not a direct replacement” for Craig Hampson

Edwards said that as technical director, Bretzman was going to have a different role from that occupied by Craig Hampson, who has joined Dale Coyne Racing, possibly to run his former championship-winning driver, Sebastien Bourdais.

Edwards explained: “Craig was remote and handled research and development. And with Andretti Autosport being the anchor team for Honda, he worked with HPD on the mapping of the aerokit.

“The thing we identified over the course of the last year or so was that asking Ray [Gosselin] to both be technical director and engineer Ryan Hunter-Reay was probably compromising what we were doing. He did a tremendous job, but when you look at Penske, Ganassi, Schmidt… One of the things I was responsible for at Schmidt was separating the lead engineer from thinking about race engineering every week.

“So we felt we needed to separate those two roles, and when we became aware that Eric was available, we felt that was a good fit for our technical director role. We looked at what he’d been doing for Ganassi in NASCAR, in terms of overseeing the overall engineering of what was going on there, and when you combine that with Eric’s tremendous experience in the IndyCar frontline, it was a great combination.

“So now with Ray’s relationship with Ryan, and the fact that Ryan is continuing with us at least through 2020, it made sense to keep that group together. Ray’s competitive nature is ideal for working with Ryan.”

Still working on fourth entry

Edwards confirmed that Andretti Autosport is still working on a fourth entry, which will continue to be race engineered by Garett Mothersead. He said: “We have four contenders we’re talking to, two of which are strong, and we’d hope to have that in place by the end of the month, if not sooner.

“One of the potentials is Carlos [Munoz]. We’d like to have him back. We know he’s looking at other options, but we’re hopeful of keeping him in the fold. Relatively speaking, Carlos had a strong year and finished highest of our cars in the championship. He also showed a greater consistency than before, and we’d like to continue building on that.”

Edwards also revealed that Doug Zister, who race engineered RC Enerson’s Indy Lights car at Schmidt Peterson Motorsports, has rejoined Andretti’s Lights squad. He previously worked at AA as Zach Veach’s race engineer, guiding the American youngster to three wins and third in the Lights championship in 2014.