The crew of Karun Chandhok, David Brabham and Peter Dumbreck completed more than 400km over the day.
The day started positively with Karun setting the fourth quickest time of the 90 minutes as he clocked 1:46.491, making JRM the fastest non-works team.
After a refuel and tyre change, he handed over to Peter as a light rain began to fall, before David brought the session to a close.
Karun again opened the second practice with Peter taking over for two runs and David again bringing the session to a close. The afternoon focused more on race preparation with longer runs on used tyres. David set the team's quickest time, 1:47.715, placing JRM 7th overall.
"We started the day very encouragingly, picking up where we left off at Aragon. The set up and the improvements we made seemed to translate straight away. The conditions were very different in the second session, with different weather and track conditions and the wind blowing in another direction.
"This morning we were clearly ahead but now it looks as though it will be a tough battle between ourselves, Rebellion and Strakka, but that is what it's all about. I don't think we are a million miles away from having a very good weekend," Chandhok said.