F1 2015, Jerez test: McLaren continue to struggle with reliability issues as Mercedes show off with 248 laps in two days

McLaren driver Jenson Button is unconcerned despite the team struggling to get to grips with their new car during the first two days of the Jerez test.

It is the first test of the 2015 season, and McLaren, who have switched power units from Mercedes to Honda for the current campaign have failed to get any mileage under their belt.

Fernando Alonso, who arrived from Ferrari, was at the wheel on the first day of the test with Button taking over from the Spaniard on the second day. Both suffered similar fates as they spent most of their time in the pits with the McLaren only completing six laps on each day.

However, the Briton is only excited to be part of the new McLaren-Honda era and understands that it will take time for them to get on top of things, but is confident that the team will get their heads around the problem along with the engine manufacturer and get going in the next two days of the test.

"It's nice to be a part of the new era of McLaren-Honda which has a very exciting future, but as we all know things take a little bit of time. The atmosphere within the team is very good, and when I say team, I mean McLaren-Honda, which is key for everyone to remember. It's not McLaren with an engine manufacturer, it's one team with one goal," Button said, as quoted on espnf1.

"It's not the easiest start to the season, but as we know it's a very complicated power unit. We will get our heads around it. In terms of the problems we had today we have our head around it and understand the issue, so we're hoping for a much more productive day three and day four," the 2009 World Champion explained.

The former Brawn GP driver is impressed with the design of the car and believes that once the team gets the mileage needed, they will have a good car to compete with during the 2015 F1 season, that gets underway on March 15 in Australia.

"The whole team have done a great job to get the car here for the first test, and if you look at the car itself, in lots of areas it is a step forward from last year's car. The car looks good in many ways in terms of packaging, the engine, it's great, fantastic. So we've got a lot of things right at the start of the year, and now it's just about putting mileage on it," Button concluded.

Meanwhile, 2014 World Champions Mercedes have continued from where they left off last season, and have been the most impressive team in the first two days of the Jerez test.

Despite Ferrari's Sebastian Vettel setting the fastest time on both days, the Mercedes drivers have concentrated on long runs rather than fast times and they have already racked up 101 more laps than their nearest competitor.

Lewis Hamilton, who took on the driving duties on the second day feels that the car has made a step forward in terms of down force, but insists that the team will continue to work harder to achieve better reliability after he suffered a water leak that ended his afternoon three hours earlier than the rest of the field.

"It feels pretty much the same, feels like we've got more downforce, so I think we have taken a step. How big? I can't say. We weren't out there trying to do fast lap times. It's good we've had such good running over the first two days, good reliability," Hamilton said.

"But we will continue to work on that which is the foundation we want to improve on. As for the water leak, I can't tell you too much about it. The team will work on it overnight and the car will be fine for tomorrow," the reigning F1 world champion added.