(CNN) -- Lotus' Kimi Raikkonen clocked the fastest time on the final day of Formula One Testing at Jerez Friday.
The 2007 world champion came home in a time of one minute 18.148sec off 83 laps with Force India's test driver Jules Bianchi in second spot on 1:18.175.
Ferrari's Felipe Massa's time of one minute 17.879 seconds, which was set on Thursday, remained the fastest time of the whole week.
But Raikkonen, who finished third in the title race last season, is encouraged by the progress made over the past four days.
"We continued our work from Thursday and made some good progress," he told reporters ahead of the next test session in Barcelona on February 19.
"We're at the top of the timing monitors, but that means nothing in testing. Our focus has been testing parts on the car, but I've been able to get the set-up more to my liking.
"For sure there's more work to be done in this area, but that's what we're here for. The car feels strong and we seem to have a good idea of where we're going with improvements. Let's see what happens in Barcelona."
Meanwhile, triple world champion Sebastian Vettel was satisfied with his day's work, despite being delayed by a pot-hole in the track.
"Everyone is on the limit here, running wide, using the maximum amount of track and the kerbs and unfortunately it started to break up," he told reporters.
"But the circuit did a very good job over lunch to get everything sorted and gave us an extra half hour at the end, so no real problem."
Vettel completed 96 laps following the 30 minute wait and the German driver was left impressed with the car's reliability.
"I think for the whole team it's been quite a good test," said the German.
"No problems in terms of reliability and we did a lot of laps, so I'm quite pleased with the results.
"I feel a bit better than last year. I think we had some issues with reliability then, so it seems we have done our homework well."