Most observers think that the small Swiss team, which almost joined Manor in collapsing recently, will bring up the rear starting in Melbourne this weekend.
When asked where Sauber really is, driver Ericsson - whose sponsors are reportedly linked with the team's new owners - told Blick: "That's the million dollar question for all of us.
"Nobody has the answer. But the tests encouraged us, because Honda and Renault had their problems with reliability, even if we are far from where we want to go.
"I think Haas is the closest to us, but forecasts are very difficult after only eight days of testing."
Sauber came 10th in the 2016 constructors' championship, ahead of only the defunct Manor.