Jarno Trulli praised the step forward taken by his Lotus team following the introduction of several updates in Spain.
Although the Italian finished four seconds off the pace in second practice, he was confident there is more to come from the upgrades, which he labeled "a major step forward."
"First day back in the car in Europe and I'm really happy with how we have progressed with the car," said Trulli. "Obviously, it's still too early to assess it properly, but as soon as I got out on track I could feel that we had taken a major step forward.
"We have solved a number of the issues we had and we're definitely in the right direction, so I'm really pleased for everyone in the team as they've put in a great effort to get us here."
Teammate Heikki Kovalainen also admitted he was very encouraged by the updates after setting the 20th-fastest time.
"I've been really looking forward to being back in Europe and particularly here in Barcelona," Kovalainen said. "It's been great to see the grandstands already busy, and I've seen a load of Finnish flags out there.
"On track, this morning was a really good session and I'm very encouraged by the updates – they're immediately working like we'd hoped. The car feels better to drive, the high-speed stability especially is better, and that's what you get when the aerodynamics of the car improve."