By Sarah Holt
BBC Sport in Valencia
BMW Sauber finished third in 2008
BMW Formula 1 boss Mario Theissen is trying to secure the future of the team after the German car manufacturer decided to quit the sport.
BMW made its decision in July following a poor season and has decided to focus on furthering its work to create environmentally friendly road cars.
The team have lodged an entry for F1 next year and Theissen said it was his "first priority" to find new owners.
"It's not easy, but there are opportunities," he said.
Team founder Peter Sauber, who has remained a minority shareholder since BMW bought the outfit in 2005, said earlier this month that the company's board rejected an offer he had made to take over the team.
But Theissen said that he and Sauber were working together on finding a solution.
"I am not working on my own, I do it together with Peter," Theissen said. "He is trying very hard to use his connections. I cannot tell you anything about the ongoing negotiations.
"There are several interested parties and we are just about to evaluate the individual proposals."
It is unfinished business in that we have not won the championship. We have achieved a lot, but not the ultimate step.
Theissen said that BMW's decision to quit F1 was not caused by the team's poor form this season.
They scored their maiden victory last year with Robert Kubica at the Canadian Grand Prix, after which the Polish driver led the world championship, with BMW top of the constructors' standings.
Both challenges ultimately faded, but BMW began this season expressing an ambition to mount a serious title challenge.
Instead, their car has been one of the most uncompetitive on the grid, although Theissen said he is optimistic the team could still make something of this season and perhaps emulate McLaren's achievement in recovering from a poor start to win the last race in Hungary.
"We are in a difficult situation we want to make the best out of it," he added.
"There are still seven races to go and we can still achieve what McLaren achieved in Hungary after a difficult first half of the season. We are still pushing even harder than before and then we will see what the future brings.
"It is unfinished business in that we have not won the championship. We have achieved a lot, but not the ultimate step."
From the feedback we had, I always thought we were safe and secure for the future
Drivers Kubica and Nick Heidfeld, who both joined the team in 2006, said they were stunned by BMW's decision to quit Formula 1.
The first Kubica knew of the decision was when he read the story on the internet three days after the Hungarian GP before receiving confirmation by email from the team.
Heidfeld revealed Theissen had tried to break the news on the eve of the official announcement but had not been able to reach him.
"It was definitely unexpected," he said. "From the feedback we had, I always thought we were safe and secure for the future.
"BMW pulling out is a bad decision for everybody involved, especially at the factories in Hinwil and Munich."
Kubica, 24, added: "It was quite a shock decision - at the Hungarian GP we knew nothing. I think everybody is still a bit worried about their future.
"Last year I was a bit upset because I felt like we didn't take our opportunity to fight for the championship.
"Now, at least in the near future, BMW never has the chance to be leading or fighting again."
While Theissen tries to guarantee the future of the team, Heidfeld and Kubica have turned their attention to finding a race seat for 2010.
Kubica was contracted to BMW for next season but Heidfeld's deal was due to expire at the end of the 2009 campaign and he had already begun discussions with other teams.
"Of course, those talks have become more intensive now over the last couple of weeks but I am confident for the future," said the 32-year-old German.
"I feel as confident as before. We are in talks with several teams and I think it is looking good."
Kubica, who is rated as one of the most talented drivers on the grid, is also determined to continue racing in F1 next season.
The Pole has been linked with a move to Renault to replace Fernando Alonso, who is expected to go to Ferrari next season, and he said: "I am pretty confident that I will find the right place to be next year.
"It's difficult to know which car will be the best and where to go but hopefully I will be in a competitive car next season
"I am quite open-minded. I think I have shown last year that once the car is quick I am able to give a bit more extra."