Manufacturers drop arbitration

Speculation had been rife for months that the three engine manufacturers were ready to launch arbitration action against the FIA because they all opposed the change in technical regulations - claiming that Mosley was not justified in using the excuse of rising speeds to alter the engine formula.

The teams claimed that under the Concorde Agreement, the document by which F1 is run, engine size was rubber-stamped at being 3-litres until the end of 2007 - and that part of a deal agreed with the governing body early in 2003 was that engines would remain at a life of one race weekend for the same duration.

After Autosport revealed on Thursday that Mercedes-Benz had decided against taking action, BMW and Honda issued a statement confirming that they too had decided to drop the legal threat.

BMW motorsport director Mario Theissen said: "The BMW WilliamsF1 team has decided, in accord with BAR Honda, not to appeal against the engine regulations ... scheduled for 2006.

"A legal challenge to the content and form of the modified regulations would take up too much time - time in which all manufacturers would be forced to undertake costly parallel developments.

"That would not be in the interests of the sport, whose future we aim to strengthen. With this decision we want to contribute to a united position of the engine manufacturers in Formula 1."

Mercedes-Benz has so far declined to comment about its plans.