Graham Rahal encouraged after first RLLR test at Sebring

Rahal completed 49 laps on Sebring's short course before thunderstorms brought the day to an early end, but he said that his time with the team had still been productive.

"The car has been extremely good handling-wise; we're right up to speed," he told the official IndyCar site.

"Laptimes aren't as quick as they were in the spring because the track just doesn't have the grip, but that doesn't matter. We're here to learn, we've tested a lot of stuff and we're making the car better.

"A lot of these guys I've known for a long time, but it's the first test day I've ever worked with them and it's been fun to kind of plug away.

"We're still a long way off from the season but we have extremely high hopes and that's what we're working toward. To get a head start, to get a few days here, means a lot to all of us."

Several teams are scheduled to run at Sebring before the testing blackout comes into force on Friday.

Rahal was expected to remain in the car until Wednesday, with others including Penske duo Will Power and Helio Castroneves, 2012 champion Ryan Hunter-Reay, rookie of the year Simon Pagenaud, and KV Racing's Tony Kanaan and Simona de Silvestro among those also set to run.

Several of those drivers will also test Wednesday, where they will be joined by the likes of Ganassi's Scott Dixon, BHA's Alex Tagliani and Andretti's James Hinchcliffe.

Conor Daly and Tristan Vautier are also slated to have their first run in an IndyCar on Wednesday for AJ Foyt Racing and Schmidt Hamilton respectively.