Ferrari's Sebastian Vettel set the fastest time on the final day of Formula 1 pre-season testing.
The four-time champion ensured Ferrari were fastest on five of the eight days in Spain.
World champions Mercedes are regarded as favourites before the first race of the season in Australia on 18-20 March.
But Vettel said: "The new car gives us the chance to close the gap. How much? We need to be a bit more patient."
The German's fastest time at the Circuit de Barcelona-Catalunya was just 0.04secs slower than the fastest time of the winter set by his team-mate Kimi Raikkonen on Thursday, on the ultra-soft tyre.
Vettel was using the super-soft, which is said to be between 0.4-0.6 seconds slower, and was 0.282 seconds quicker than Toro Rosso's Carlos Sainz, who was on the ultra-soft tyre.
Headline lap times in pre-season testing are a notoriously poor guide to form, as they are subject to a huge number of variables and teams do not reveal the specification in which their cars are running.
Williams' Felipe Massa and Force India's Sergio Perez were next on the super-soft tyre and world champion Lewis Hamilton fifth on the medium tyre, 1.6secs down on Vettel on a tyre regarded as about 1.7secs slower than the super-soft.
Nico Rosberg believes there will be little between Mercedes and Ferrari in Australia.
"We know that Ferrari is very close," he said. "They've been very quick.
"All of the teams have their strategists, so we know more or less what fuel the other teams are running and they know our fuel. So we know more or less where we are compared to Ferrari - that's why I say it's close.
"But we're not sure if we are ahead or behind."
Mercedes have shown remarkable reliability over the testing period and have done so many miles that they have been using two drivers per day rather than the normal one to avoid tiring them out.
However, they had their first on-track stoppage because of a transmission problem on Hamilton's car shortly before lunch on Friday.
Hamilton said: "Best test ever in terms of how many laps, but it is not the best test in terms of it gets a bit boring after a while going around and around without learning too much.
"It has put us in a good position for the first race, but I have never been a fan of testing. It's been gruelling.
"The car just goes and goes and goes. So on one hand it has been great; on the other it's like: 'Oh my god, how many more laps have I got to go?'"
Hamilton said he was pleased to have the reliability problem in testing so the team could fix it in time for the first race.
Jenson Button was seventh fastest in the McLaren-Honda on ultra-soft tyres, just over 0.1secs quicker than the Renault of British novice Jolyon Palmer on super-softs.
1 Sebastian Vettel (Ger) Ferrari 1:22.852
2 Carlos Sainz (Spa) Toro Rosso 1:23.134
3 Felipe Massa (Brz) Williams 1:23.644
4 Sergio Perez (Mex) Force India 1:23.721
5 Lewis Hamilton (GB) Mercedes 1:24.133
6 Daniel Ricciardo (Rus) Red Bull 1:24.427
7 Jenson Button (GB) McLaren 1:24.714
8 Jolyon Palmer (GB) Renault 1:24.859
9 Marcus Ericsson (Swe) Sauber 1:25.031
10 Romain Grosjean (Fra) Haas 1:25.255
11 Esteban Gutierrez (Spa) Haas 1:25.422
12 Rio Haryanto (Idn) Manor 1:25.899
13 Nico Rosberg (Ger) Mercedes 1:26.140
Vettel, Massa, Perez, Palmer and Gutierrez set their best times on the super-soft tyre, Sainz, Button and Haryanto on the ultra-soft, Ricciardo, Ericsson, and Grosjean on the soft and the Mercedes drivers on the medium