Jerez, Spain - Ferrari has made improvements in all areas and its new Formula One car is a "completely different story" to the one that drew a dismal blank on the track last year.
Kimi Raikkonen said on Tuesday, after his first day of testing: "The whole package is quite a bit better from where we finished last year. We've improved in all the areas.
"We have a lot of things to do and things to improve, but it's definitely a positive start and we have something to work with."
Ferrari failed to win a Grand Prix in 2014 for the first time since 1993 and Raikkonen endured his worst season in the sport, finishing 12th overall and without a single podium appearance.
The team had three team principals last season in a major shake-up, with the most recent Maurizio Arrivabene arriving in November.
He has set a minimum target of two wins in 2015.
Four-times world champion Sebastian Vettel has arrived to replace departed Fernando Alonso and lapped fastest in the first two days of testing, although times are less important at this stage than mileage covered.
Raikkonen, who did 92 laps equal to 407km on Tuesday, ended the day second fastest behind Brazilian rookie Felipe Nasr in the Ferrari-powered Sauber.
"You usually know if a car is good or not," said Raikkonen, "and this year is a completely different story than last year as I had a good feeling straight away when I went out."
While Mercedes again completed the most laps, with Nico Rosberg doing 151 at the wheel on Tuesday, Ferrari's improved performance has been noted by its rivals.
Rosberg said: "We are keeping an eye on the opposition, especially Ferrari has been an eye-opener in the last couple of days."
Australian Daniel Ricciardo, Vettel's team mate last year at Red Bull, agreed.
"The time Seb did yesterday was quick," he said. "I don't know about fuel and tyres or whatever, but it was a good time. Ferrari looks good for now."
McLAREN CALLS TIME
McLaren's new Honda-powered car showed progress on Tuesday with Fernando Alonso completing 32 laps before an engine problem forced an early end to its penultimate day of testing at the Jerez circuit.
Before Tuesday, Alonso and team-mate Jenson Button had managed only six laps each in the MP4-30 turbo hybrid car on the opening two days of the first pre-season test in southern Spain.
"We've had a loss of cooling water pressure and have removed the power unit for inspection," the team said. "That's a long process, so it ends today's running.
"We can replace those components ahead of running tomorrow," it added, as the team missed the final three hours of Tuesday's session.
McLaren is starting a new partnership with Honda, which powered it to titles in the late 1980s and early 1990s and is returning after leaving the sport in 2008, after two decades with Mercedes.
Double world champion Alonso, who had one acrimonious year with McLaren in 2007 alongside current world champion Lewis Hamilton, has joined from Ferrari.
McLaren and Alonso had warned before the test that there would be problems with bedding in the new V6 engine and they have been proved right.
The number of laps completed in the morning did at least show, however, that the problems that sidelined Button on Monday had been addressed.
Button, who will be at the wheel for the final day on Wednesday, had said on Monday evening: "We expected it to be difficult. I'm sure the next two days won't be plain-sailing either.
"It's going to be tricky. It's a very complicated power unit, it's not as straightforward as the old V8 engines or the V10s. So it takes a little bit of time."
MERCEDES RUNNING LIKE CLOCKWORK
Champion Mercedes, which dominated last season with its engine taking Hamilton to his second title, continued to run like clockwork after completing more laps than any of their rivals.
Nico Rosberg had little to worry about on Tuesday, completing 151 trouble-free laps, but did express concern about the uncertainty hanging over his home German Grand Prix.
has a race scheduled for 19 July but neither the Nurburgring nor Hockenheim circuit has so far agreed to host it.
Formula One commercial supremo Bernie Ecclestone warned on Monday that the race was looking unlikely due to commercial reasons and past poor attendances at both venues but said he was trying to rescue it.
Rosberg, whose mother is German and his father Finnish world champion Keke, said he was saddened to hear that nothing was confirmed.
"For as long as I can remember, the German Grand Prix was part of the Formula One World Championship, so I really hope our Grand Prix will be held this year and beyond that," he said after the third day of testing in southern Spain.
"The fans deserve to have a great show every year because there are so many great supporters out there. Also there is plenty of Germany in F1, with us German drivers such as Sebastian Vettel, Nico Hulkenberg and myself, plus of course Mercedes-Benz," added the 29-year-old.
"So I really hope that Bernie and the promoters find a good solution for everybody."
Rosberg won the 2014 race at Hockenheim, becoming the first winner for Mercedes in Germany since Argentine Juan Manuel Fangio in 1954.
He was also the first German home winner for a German team since the championship started in 1950 but, despite his team's domination, only 52 000 people attended on race day.
Reuters