Toto Wolff has played down reports Mercedes is the clear 2014 favourite after the first winter test at Jerez last week.
"It is too early to know," the German marque's commercial director told the Spanish-language Motorpasion.
"It is just testing and so you can't say much. But it was good that we were able to do so many miles, Nico Rosberg even did a race simulation, which is something the others were not able to do.
"Only in Australia will we see something representative," added Wolff. "The cars are going to change a lot until then, (as) there is a lot more testing to do."
German Rosberg agrees that, while Mercedes had a successful test in southern Spain with good reliability, "a lot of work" still lies ahead before Melbourne.
"Performance-wise we don't know where we are because you can't really compare to the other cars, but that's not the focus right now," he insisted.
Teammate Lewis Hamilton added: "It's a bit early to say this definitely, but right now the car feels pretty good.
"So far so good; now we just have to continue working hard and see what happens in Bahrain."
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