McLaren are confident of challenging Ferrari in this weekend's German Grand Prix after improving their new car.
Raikkonen and McLaren pushed Ferrari at Silverstone
Kimi Raikkonen impressed at the British Grand Prix in only the car's second race, and it will feature aerodynamic upgrades at Hockenheim.
"The results of the test were encouraging and have shown that there is more to come from the car," he said.
The Finn's team-mate, David Coulthard, said: "The car has progressed in chassis and engine performance."
Raikkonen set pole position and finished second to Michael Schumacher at Silverstone, only a week after the MP4-19B made its race debut at the French Grand Prix.
The car has proved to be a major step forward over the troublesome MP4-19 with which the team started the season.
McLaren completed an intensive test programme last week, running cars simultaneously at Silverstone and Jerez in Spain and employing test drivers Alexander Wurz and Pedro de la Rosa as well as Raikkonen and Coulthard.
Raikkonen said: "The result at Silverstone and the pace of the MP4-19B during the weekend was very positive for the whole team.
"I felt competitive all weekend and am looking forward to taking this form to Germany."
Martin Whitmarsh, the chief executive officer of McLaren's F1 team, said: "We have continued to push hard with our development programme.
"We have conducted two intensive tests at Silverstone and Jerez, with all four drivers in action, completing over 3800 kilometres in total.
"The simultaneous programme included Hockenheim set-up work and the proving of new components that we will race at the German Grand Prix.
"This was in addition to developments that will be introduced in the longer term, which were tested at this time because of the testing ban that is now in force until the first week of September."