Grosjean completed 95 laps of the Spanish circuit.
"It was good today; the programme went to plan and we showed we have good reliability," he said.
"For me, the whole test has gone well which bodes well for the year ahead. My feeling in the car is good and it was great to be at the top of the times. Even if it doesn’t mean anything during testing, it’s still good to be at the front.
"We used the soft, medium and hard compounds and whilst we’re not 100% yet on the differences between each we have a good idea. Kimi [Raikkonen] will be working on this area for the next two days so we’ll have a better understanding when we head to Barcelona. It’s not easy to understand everything about the car and tyres yet, but I think we’re working quite well and it’s up to us to find the best solutions."
The team also confirmed that Grosjean's stoppage towards the end of the day was down to a planned fuel test.