Felipe Massa, who clocked the fastest overall time at last week's Jerez test, has declared the Ferrari F138 "better" than its predecessor. "It's more consistent, better in braking, in and out of the...
"It's more consistent, better in braking, in and out of the corners and easier to understand," he is quoted by Brazil's O Estado de S.Paulo newspaper.
The Italian team's experienced new test driver Pedro de la Rosa, who tried the 2013 car on Friday, agreed: "The car is well balanced and responds well to changes."
He told AS newspaper: "There are no problems, but until the end of the Barcelona tests it's absurd to draw any further conclusions."
Ferrari president Luca di Montezemolo told Italy's Sky Sport 24 that the F138 is "in line with what we expected".
"But the one we are testing is different to the car that will start the season," he added.
Lotus' Kimi Raikkonen was fastest as the Jerez test concluded on Friday.
But Niki Lauda - F1 legend, German-language commentator and new Mercedes chairman - thinks Red Bull has "the best" car after the first week of pre-season running.
"After that I see a group with McLaren, Lotus, Ferrari and us (Mercedes)," the triple world champion said.
Jo Ramirez, the former long-time McLaren team manager now involved with countryman Sergio Perez, agreed: "Red Bull, McLaren and Lotus are fast and consistent.
"Ferrari is next and then Mercedes, but the differences are small.
"It will be another hotly contested championship."