Lewis Hamilton has called on Mercedes to keep improving the W10 after the first pre-season test in Barcelona.

On the final day on Thursday, the defending world champions upped their pace as both drivers conducted short runs on the softer Pirelli compounds, ending in the 1m17's.

However, it only put the marginally ahead of rivals Ferrari who continued on the slower C3 tyre with many believing it is the Brackley-based team playing catch up.

"In general, the car was feeling better today and is coming together. However, we still have to keep on digging deep, analysing the data and the changes that we are making," Hamilton commented.

"The reliability has been really solid which is a great showing of all the hard work that everyone in the factory has done, but we have to keep on pushing, the competition looks very strong."

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Both Hamilton and Bottas shared driving duties on all four days and ended with the most laps of any team with 610, more than five race distances around the Circuit de Barcelona-Catalunya.

"We've been making progress throughout the entire week, the car felt better every single day," Bottas added. "We're now looking forward to next week when we will hopefully make even more progress.

"Many thanks to the entire team, it was a good first test. Now we're all hungry to improve even more in the second test."