Lewis Hamilton has been enjoying his driving since pre-season got underway, with Mercedes running untroubled through its successive programs.
The Brit completed his first race simulation of 2017 before rounding off the day with further aero setup tests and pit stop practice.
"It's been a great test so far for the team," said the three-time world champion.
"Everyone at the factory has worked so hard to build a car that goes the distance. As always on these test days we're trying to get through as much as possible, in terms of reliability.
"The main thing is I got my first race run done today with no problems at all. Everything's worked well, which I'm happy about. The car is running smoothly and we're just running through setup items to tick off boxes at this stage. "
Despite Mercedes consistently sitting at the top of the leaderboard, Hamilton insisted that the ultimate lap time was of no interest, for now.
He also praised team mate Valtteri Bottas for his precious contribution as he progressiveley unlocks the W08's potential.
"This is testing, so on the first week you never chase times. When you bring out a new car you don't have all of the components to be able to switch and make changes and work through everything you want to do - that's something that filters through over the days.
"Next week we should have a better opportunity to dial in the car, but for now we're focusing on mileage.
"Valtteri is doing a great job so far. His feedback seems solid, he's working great with the team and transitioning in smoothly. "
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