Williams to Honda, Bridgestone; Heidfeld to BMW?

Further to the rumour that BMW is considering buying Peter Sauber's eponymous team to ramp up its Formula One efforts comes speculation that Williams will return to Honda power from 2006, but lose the increasingly impressive Nick Heidfeld to its current engine supplier.

Although BMW's Mario Theissen insisted that it would be at least a month before any deal with Sauber - be it full buy-out or mere engine supply - would be confirmed, and that the Munich marque was happy to continue with Williams, the comings and goings at the Nurburgring this past weekend could not help but spark the rumour mill into new life.

Williams is understood to have held preliminary talks with Cosworth and Toyota as well as Honda, but more fingers point to the latter - currently heavily involved as shareholder at BAR - as the most likely partner for 2006. The present Honda engine is rumoured to be the most powerful on the grid, and came through a key test at the European Grand Prix when both Jenson Button and Takuma Sato finished despite their V10s having sat, untouched, on a shelf at Brackley since the San Marino round. The Japanese company is thought, however, to be concentrating on a single engine supply, and no customer deals, for the foreseeable future.

Toyota, meanwhile, has a customer deal in place for 2005 with Jordan but, with the Silverstone-based team's future still clouded - and moreso following the Monaco rumours that Alex Shnaider was looking to sell up - possibly opening up a relationship opportunity with Williams. Finally, Cosworth has its 2006-spec 2.4-litre V8 ready and waiting for an offer, following Red Bull Racing's decision to use Ferrari power next season, and Minardi's inability to afford a switch away from restricted V10s.

Should BMW and Williams go their separate ways next season, it is thought that Nick Heidfeld, complete with two second places in recent grands prix, would follow the German half of the partnership, effectively returning him to Sauber, which rescued his F1 career after a disappointing debut with the ailing Prost operation. That, in turn, would open up a seat for Jenson Button to complete his switch from BAR - despite CEO Nick Fry's best intentions. Moving to Williams would also, possibly, keep the Briton Honda-powered, something that Fry was counting on as a reason to keep Button at BAR.

One final rumour surrounds Williams after the weekend - that the team may decide to ditch its Michelin contract and move over to the Bridgestone camp. Sir Frank Williams was apparently spotted deep in conversation with Bridgestone's Hiroshi Yusakawa, who is thought to be trying to recruit more teams to his company in an attempt to bring Bridgestone back into the frame after a disappointing start to 2005. The Japanese company relies heavily on Ferrari's input from testing, whereas Michelin can call on leading runners such as McLaren, Renault, Toyota and Red Bull, as well as Williams. Interestingly, given the whole Williams-BMW-Sauber triangle, the Swiss team defected in the opposite direction at the start of the current season...