The new Lotus struggled early on in Spain, but completed numerous laps towards the end with few problems.
Grosjean says that the signs for the coming season are positive.
"I've been lucky in that every time I've jumped in the car things have gone well, but the main thing is that the team has managed to get some good mileage on the board," Grojsean told Lotus's official website.
"We've completed a full race simulation and a bit more on top of that during my first day on track without any issues, which is a big positive.
"Also, when you compare our performance during that long run with other teams, the pace looks competitive, so there are plenty of encouraging signs."
The 2013 season begins in Australia during the weekend of March 15-17.