Monisha Kaltenborn has fired a shot at Sauber’s former race drivers.
For 2015, the Swiss team dispensed with its 2014 lineup of Adrian Sutil and Esteban Gutierrez, instead signing Felipe Nasr and Marcus Ericsson.
Nasr and Ericsson have been described as ’pay drivers’ who are now helping to finance the struggling Hinwil outfit.
German Sutil, meanwhile, is now Williams’ reserve driver, while Mexican Gutierrez is filling a similar role at Ferrari.
Boss and co-owner Kaltenborn, however, said Sauber is now much happier with Brazilian Nasr and Swede Ericsson.
"The drivers are making a big difference," she told Brazil’s Globo.
"They work very well with the team and are learning a lot."
As for Sutil and Gutierrez, who last year failed to score a single point, Kaltenborn said: "It was not easy for them, and it’s not fair to blame them.
"We did not give them a good car," she added. "But it is also true that our drivers today have a very different attitude and we can feel that."