It is a common myth with McLaren fans that Mercedes and McLaren have an unconditional supply deal until 2015. This is not true. Under certain conditions McLaren could be a Mercedes customer until that time.
Mercedes press release 16.11.2009 wrote:source
The partnership between McLaren Mercedes has been in place since 1995 and
ended its 15th joint Formula 1 season
in 2009. The
change to the form of
cooperation is taking place by mutual agreement. Mercedes-Benz and McLaren will continue to co-operate with each other and
the supply of engines could continue until 2015.
But that is far from certain. The previous partnership agreement between the companies extends until the end of the year 2011. Then McLaren's exclusivity and veto rights for F1 engines come to an end as the Mercedes share holding in the McLaren group. It is clear from the Mercedes 2009 press releases that Mercedes can stop supplying McLaren if they see the need for such a move. Equally McLaren can select a new source of engines.
The question is why should any of the two parties terminate the current deal? It will not make any sense for next year. McLaren cannot find a better engine and Mercedes may need McLaren victories to continue a success story. There is some limited sense for McLaren in building an own engine for 2013. I reckon they will probably do this with a competent partner, but if it goes wrong they will probably try to retain an option to run the turbo Mercedes.
Something that has always been humbug is the idea to buy the BMW F1 engine team. There was never such a thing as the BMW F1 engine factory. The engine teams were distributed across many locations in Munich and Landshut. The core parts of the engine were manufactured in Landshut where a lot of BMW high tech projects are located. Among others all the high tech light alloy casting
is done there but they also do things like the Rolls Royce aluminum raw chassis there.
The development team was partly pulled together from Motorsport GmbH but also from the FIZ (Corporate Development and Research Center). These teams have long been broken up and dedicated to other projects. Beside intellectual property on paper and disks there is nothing McLaren could buy from BMW. They could head hunt the former employee list of BMW F1 but whatever could have been gained from that will have been done by other parties long ago.
The question if an own engine makes sense to have from 2013 will partly be decided by the RRA negotiations. It is obvious that the independent teams will try to limit the capability of engine suppliers to run away with a big competitive advantage. As the independents have the majority in the F1 commission they will probably be able to set all technical and sporting rules. They will only get a signature under an engine RRA - or a comprehensive budget cap including engines - if they offer terms that can be accepted by the manufacturers. I guess the framework for that is already fixed in its majority. In the fulness of time it will be revealed and we will also learn what McLaren plans for 2013-2017.