Esteban Guttierez is in little doubt that Ferrari's upgrade has more potential after testing the SF15-T at the Circuit de Catalunya on Wednesday.
Ferrari arrived at last weekend's Spanish Grand Prix with overhauled bodywork as the team attempted to close the gap to championship leaders Mercedes. However, the gains the team had hoped for failed to emerge over the weekend and Kimi Raikkonen reverted to the old bodywork to run a comparison in the race.
Gutierrez tested the car on Wednesday with the aim of understanding why the new package did not deliver the step forward the team had hoped for and said a big part of the problem was optimising the set-up to exploit the true potential of the car.
"The new package is better and you could see it already from the race when Sebastian [Vettel] was in a better shape overall with the package [than Raikkonen without it]," he said. "Today we could prove that and there was a bit of a difficulty in the way you have to set up the car in the package and this was one of the things that was interesting to prove in this test."
Gutierrez said the idiosyncrasies of the Circuit de Catalunya had not helped Ferrari maximise its potential at the weekend.
"Barcelona is a very tricky track with the high temperatures and as soon as you get to midday and the afternoon the track changes so much. It's hard to say how the performance of the car was, because I think the tyres were a bit stiff for this track and Monaco will be a very different case. We will have to see how the car gets going there." It was Gutierrez's first taste of the SF15-T after several days of testing its virtual counterpart in the Ferrari simulator.
"It's quite impressive actually, it's the first time I've driven this car and the feeling straightaway is positive and very different to what I was used to. I'm really grateful because I could really feel how everyone in the team was really looking forward to me testing the car, because I'd been a lot at Maranello and in the simulator testing the car a lot of time and now it will be interesting to correlate that into the simulator and keep up the development."