BMW Sauber's head of engineering Willy Rampf believes his team has taken a step forward thanks to the updates introduced for the Spanish Grand Prix.
The tech chief, however, said it was too early to quantify the improvement and he reckons the picture will not be clear until tomorrow's qualifying.
"We have come to Barcelona with a comprehensive aerodynamic package. To find a basic set-up was today's main task. A first evaluation of the aero data shows we made a step forward," said Rampf. "Now we are curious about the first real comparison in Saturday's qualifying to see where we really stand in relation to the competitors."
Robert Kubica and Nick Heidfeld finished in 16th and 17th positions respectively in Friday's practice, the German losing track time in the morning after having brake issues.
"Unfortunately I lost some time this morning when we had a couple of problems during the first free practice session," Heidfeld said. "Only at the end was I able to work properly on the program. That was a shame because with such a new package and, for me, driving the car for the first time without the KERS, track time is especially important.
"Considering the small amount of mileage from the morning, we made quite good progress when preparing the car for the second session, and I think there is room for more improvement."
Kubica added: "Today was a special Friday because we have a lot of new aerodynamic parts on the car. We spent quite some time working on the setup and tried different things. We now have to analyze the data so we can exploit the potential of the car to its maximum.
"In addition, as usual on the Friday, we compared the two tire compounds, but it was very soon obvious the option specification gives better performance."