Ryan Hunter-Reay tries Ed Carpenter Racing's IndyCar

Andretti Autosport did not participate in the test, however Hunter-Reay spent the morning running in Carpenter's car before handing it over to Carpenter in the afternoon.

The teams followed a similar arrangement in testing at Fontana last year, when Marco Andretti worked with Carpenter's team.

"This is an interesting opportunity, and different to usual," said Hunter-Reay.

"But Ed and I are good friends. We were team-mates in 2009 [at Vision Racing] and have remained friends off the track as well.

"We found an opportunity to work together and develop a few things, so that's what we're doing today.

"It makes sense for all involved, and I get a different perspective on things, and Ed Carpenter Racing being a one-car team gets a different perspective as well. So it's a good opportunity.

"Any time you read that IndyCars are testing and you're sitting at home it's the worst feeling, because you feel like you're sitting in the classroom while everybody else is in the playground, and you also know that everybody else is moving forward. So I am definitely thankful for being here."

Carpenter, who won last year's season-finale at Fontana, said that it made sense for the Chevrolet teams to cooperate with the aim of helping to progress the overall Chevy package.

"This goes back to something we started talking about in the off-season," he said.

"One of the great things about being a part of Team Chevy is that we really do work together, and this is a part of that. Marco ran my car at Fontana when we did the Chevy test out there, and this is kind of part two."