Lewis Hamilton says he has been astonished by Mercedes' exceptional reliability during the first pre-season test in Barcelona as the defending champions sent out an ominous warning to its rivals.

Coming into the 2016 season looking to consolidate its substantial advantage over the competition, though Mercedes didn't give much away in terms of performance as it focused on reliability, it achieved the latter by completing a mammoth 675 laps over four days.

The equivalent of more than 10 Spanish GP races, though Hamilton was aware Mercedes were making bold claims about mileage for the test, he didn't expect to surpass them.

"Really it's just been an incredible week of testing for us and before we came here they were talking about doing 800km a day and I thought that was crazy because I've never done that in the past," he said. "Usually you have breakdowns in the car, but even not just for us there is no breakdowns and a lot of reliability, which I guess you would expect with the third year of these regulations.

Having refrained from using soft tyres over the course of the week, Mercedes will bring more performance orientated runs into its programme for the second week, with Hamilton looking forward to testing the W07 at pace.

"I personally feel physically good. The training has been hard work and I'm getting older! But the car looks fantastic, we don't know the pace of the yet but what we can say is that it will go the distance. That's half the battle, but I don't think it's slow."