Alonso is still very much involved at McLaren, taking up the new role of team ambassador, despite announcing he was leaving Formula 1 this season. He joined the Woking team for the second and final week of pre-season testing in Barcelona.
Alonso hasn't driven the MCL34, but from what he's heard from the engineers, he is impressed with the team's new machine.
"I think we are learning a lot," Alonso told Autosport. "I was in contact with the team and I was aware of the debriefs and all the small problems and issues we were finding, and I think last week we confirmed the picture of the car.
"So I think there are a couple of areas that need to be revised and they need to keep developing to improve the performance. Some others are surprisingly good, so I'm happy with the results and generally I think it has been a very positive two weeks.
"It's not perfect yet, but I think the direction seems to be the right one."