Gerhard Berger hopes Sauber will now be "good enough" to succeed with Audi backing.
It has emerged that the VW-owned German carmaker has bought into the Swiss-based team currently known as Alfa Romeo - with an eventual 75 percent takeover thought to be in the works.
In the past, Sauber was allied for a time with BMW - with F1 legend Berger once a joint motorsport director with that German manufacturer.
"Sauber did not consistently adopt the BMW mentality," Berger now tells Auto Motor und Sport. "They kept the Sauber culture.
"I don’t want to say it wasn’t good, but it certainly wasn’t good enough to win the world championship."
Berger, 63, was also asked about Formula 1 more generally - and he says the all-new 2022 chassis regulations ultimately delivered a "relatively weak show".
"It was quite surprising that Formula 1 advertised so much for a relatively weak show," he said.
"While I’m happy for (Max) Verstappen, his dominance has also resulted in a lot of boring races. You always hope for three or four teams that can fight for the win.
"I do expect Mercedes to make a comeback this season. They took an aggressive approach to 2022 and it didn’t quite work out. Which happens.
"But they now know where the problems lie and they can tackle them to play a role in the championship again," Berger added.