Kimi Raikkonen says Alfa Romeo has started to dig deeper into the set-up of its C38 contender, but the Finn insists it's still about guess work for now.
The 2007 world champion viewed his new team as an unknown quantity at the outset of pre-season testing, but admitted that Sauber had actually designed and rolled out a well-balanced racing car.
"When we got the car, it's been working well and been really nicely balanced," said Raikkonen.
"Last week we didn't really do a lot of set-up work but we tried a lot of things today, just to see what happens when we change parts.
"So far, it's OK. I don't know where we are. It's guessing from our side, we only know what we do."
The Swiss outfit's positive performance so far in Barcelona appears to put it in the running for a top spot among F1's mid-field contenders. But like its rivals, Alfa Romeo Racing's new-spec charger is a work in progress.
Raikkonen is hoping the team can settle by the end of the week on a good set-up compromise before it heads to Melbourne.
"There's always a lot of things and we always run out of time every year, but that's the same as everybody," the Iceman added.
"We'll try to put things where we think it's best now, do our programme, and see what we get in Australia.
"Every circuit is different, especially Australia, it's a street circuit. So we need to have an idea if the set-up is not where we want, what are we going to do.
"That was really today we tried to figure out."
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