Q&A: BMW's F1 exit

BMW say they want to focus on sustainability and the environment. They will stay in series that allow them to transfer technology more directly, such as world touring cars. Board member Klaus Draeger said the main reason was "not our current performance or the general economic situation".

However, the fact that BMW-Sauber have scored just eight points this season, after being title contenders last year, cannot have helped. Nor can the team's lack of big sponsors or the decision by the teams' body FOTA not to continue in 2010 with the KERS energy recovery system that BMW had backed strongly.

A new commercial agreement between all teams, the governing FIA and rights holders that would have bound them to Formula One until at least the end of 2012 may have something to do with it. The FIA expects the new 'Concorde Agreement' to be ready for signing by the end of this week.

With just four manufacturers next year, assuming the rest stay. However, three new teams have been accepted, all powered by Cosworth engines. Other teams who had their applications rejected could be interested in taking any vacated slot, but the immediate emphasis will be on keeping the former BMW-Sauber team in business. FOTA say they will help.

The team's location, in Switzerland, could be a problem but not insurmountable. Founder Peter Sauber remains a consultant and 20 percent stakeholder but, at 65 years old, the cigar-smoking Swiss is unlikely to want the stress of day-to-day involvement even if he is sure to be involved in any immediate rescue effort.

BMW-Sauber employ about 430 staff at the Hinwil factory in Switzerland, which includes a state-of-the-art wind tunnel.

Toyota (yet to win a race since their debut in 2002) and Mercedes, who partner McLaren, have said they remain committed now costs are being addressed. Fiat-owned Ferrari also seem sure to stay, having an unbroken 60-year involvement in Formula One.

The main question mark hangs over Renault, who have to fill a big hole in their team budget left by the departure at the end of the year of title sponsor ING. The former champions have been struggling this season and have also just been suspended from the next race in Spain.

The balance has now tipped more (in terms of numbers) towards the independent teams, who will make up nine of the 13 entered for next season assuming BMW live on in another guise.

Red Bull and Brawn have already shown this season what privately-run teams can do. However, the manufacturers will still have plenty of clout with their considerable resources. Glamour team Ferrari and McLaren are not about to fade away.

Mercedes currently supply three teams and are keen to add a fourth, with paddock speculation suggesting Red Bull are mulling a switch from Renault. Sauber, bought by BMW in 2005, entered Formula One with Mercedes back in 1993. Sauber also used Ferrari engines, under the badge of Petronas, for nine seasons until BMW arrived. Ferrari have supplied several teams in the past but only Toro Rosso at present so could have spare capacity.

Poland's Robert Kubica is a race winner, still only 24 and highly rated in Formula One. He is likely to be snapped up by another team quickly enough. Nick Heidfeld's future is less certain. The German is now 32, in his 10th season and has yet to win in 160 starts.