Norbert Haug has added yet another F1 manufacturer's opposing voice to plans for a standard engine formula.
The German, representing McLaren's carmaker partner Mercedes-Benz, told Auto Motor und Sport that he does not "believe a single engine is feasible for the manufacturers".
Haug said F1 remains a technical challenge, but notes that "in recent years, technical excellence has been limited".
Mercedes therefore joins Ferrari, Toyota, Honda and BMW in spelling out their distaste at the prospect of a third party supplying either an engine or a mandatory detailed design in 2010 and beyond.
Toyota and Ferrari this week threatened to quit F1 over the issue, but Haug told Bild newspaper that he is hopeful a "solution can be found, but everyone must be prepared to compromise".
BMW's Mario Theissen explained to the German news agency DPA: "We don't expect the standard engine to come after the talks held so far, and our formula one concept is based on this."
Renault boss Flavio Briatore told the Welt newspaper that, instead of standard engines, F1 will "probably" pursue the route of a future engine formula that, "on the basis of costs, will not go beyond certain development borders".