Lewis was first to drive the W09 on Friday, focusing his attention on race simulations and racking up 97 laps during his final stint in the car before the season officially begins.
His best time of 1:19.464 may have left him in 11th on the leaderboard, but the Brit wasn't going for lap times and his was set early in the morning on the Supersoft tyre.
In total, the four-time World Champion left Spain with 456 laps under his belt in the new car.
"It's been a really positive test," Lewis explained. "We got through everything, reliability has been great. Everyone has been working their backsides off and doing a tremendous job, I'm really proud of the team. We're happy with the information that we've got.
"Both the car and the track are a lot faster compared to last year's race here. In my last run during the race simulation today I was doing 1:19s - that's my qualifying lap time from 2017 every lap.
"It's still difficult to know exactly where we are in comparison to Red Bull and Ferrari and we won't fully know that until we get to the first race.
"But I feel like we've got as much information as we could in order to equip us with the best data to go to the season opener. The preparation has been really good in the time that we had."