Technical director Pat Fry said there was “still room for improvement” with just nine further days of running before the first race of the season.
Felipe Massa and Fernando Alonso have failed to set any impressive times so far with the new F2012.
Fry said the team were struggling to make the car handle consistently.
Ferrari have deliberately taken a different approach to this car than to last year’s machine in an attempt to close the gap to world champions Red Bull – the Italian legends won only one of the last year’s 19 races.
But their decision to push for an “aggressive” design has meant they have spent the first three days of testing in Jerez in Spain this week simply trying to understand how to make the car work.
“The basic platform is okay,” Fry said. “We are looking at the various characteristics of some of the bits we have to test.
“We can play around with the three corner characteristics, so we can do different things at corner entry, mid-corner to exit, and it is really trying to find the right balance of those things.
“On each run we are trying almost a different configuration. There is a lot of analysis here and then back at the factory.
“We are using the simulation and the simulator to make sure everything ties in, so we can put the right package together.”
Fry said the team were not interested in putting the car into a qualifying-style configuration with low fuel and new tyres to try to set a headline lap time.
“We are not concentrating on taking the fuel out and trying to set a lap time,” he said.
“With only 12 days of testing before the first race, we have to make the most of all the time we have got.”
Last year, Ferrari’s preparations were set back when they discovered that results they were getting in the wind tunnel were not being matched on the track.
Ferrari had insisted last season that this correlation problem had been solved, but Fry admitted there was still a small concern in that area.
“There’s reasonable correlation,” he said. “I certainly wouldn’t say it was perfect.
“There is still room for improvement. I don’t think I could ever sit here and say it’s perfect. We have found some more issues since we have been here.”
Fry said the difficulties with the car were not related to the radical pull-rod front suspension – where the arm goes from the top of the wheel to the bottom of the chassis rather than the conventional way of the other way around.
He described that as “not that big a deal”, adding that it created a “small aero benefit, a small centre of gravity benefit”.