Wolff: Mercedes making its 'best start' to F1 tests of recent years

Mercedes has displayed bulletproof reliability by racking up the miles at Barcelona, while Nico Rosberg comfortably set the fastest time on soft tyres on the first day of the second test.

This form has resulted in various drivers, such as Williams's Valtteri Bottas, suggesting Mercedes is unlikely to be challenged early in the season.

Wolff said: "If drivers are saying that it is flattering, but also that doesn't win us races. It's still early days. It's pre-season testing.

"I don't want to undervalue what we did. If we compare '16 to '15, and '15 to '14, considering the regulations are stable, we've optimised around those regulations and the cars are more reliable, everybody is doing more laps.

"I've the feeling it's the best season's start we've had in the last couple of years.

"But again, we still haven't seen what the other frontrunning cars are capable of extracting performance wise. We've haven't seen Ferrari, Williams, Red Bull.

"So let's keep our feet on the ground and see where we end up on Saturday afternoon in Melbourne, which will give more indication."

Wolff declared himself "definitely happy with the amount of laps we've done", which was approaching 900 on the morning of the second day of the second test on Wednesday.

Over the first test Mercedes effectively clocked up 500 miles per day, a target Wolff concedes he thought was not possible when plans were drawn up.

Wolff was not alone in such disbelief as Lewis Hamilton claimed last week he thought the idea was "crazy".

"I was actually sceptical it would be achievable, and we've achieved it," said Wolff.

"Doing this amount of miles gives you a great opportunity to test the systems and the various components, collect data, try various set-ups because all that is going to play a very crucial part in the season.

"We've seen the better you come out of the blocks, the more miles you collect at the beginning, then the more it helps you at the start of the season.

"I'm carefully optimistic this is a good start, and it shows our preparation has been right.

"But is it going to make us win races easily? No, that's not set. It's a completely different topic."