Norbert Haug has played down the apparent superiority of Mercedes-Benz's formula one engine.
Between the Brawn and McLaren teams, the Brixworth (UK)-built V8 units - also fitted to the Force India car - have won eight of the twelve grands prix so far in 2009, and speculation indicates both Red Bull and Williams may also want to use the engines next year.
But Haug, the German manufacturer's motor racing director, told Auto Motor und Sport that it is simplistic to say therefore that Mercedes' is clearly F1's best engine.
"It is a fairytale if anyone says we have 30 horse power, or three tenths more, in our engine.
"Of course we wouldn't mind if that was true, but actually there are not such big differences (between the different engines)," said Haug.
Amid the current freeze in engine development, the FIA keeps a close eye on differences in performance, having for example allowed Renault to catch up with its rivals at the end of last season.
Haug confirmed the FIA's interest in this area and said the governing body uses tools including "sound analysis" to gauge precisely the ongoing state of affairs.
The German also played down the rumblings about fuel consumption, after Giancarlo Fisichella and Kimi Raikkonen suggested after their Belgian GP battle that the Mercedes uses less fuel per lap than its rival engines.
Haug suggests there are different reasons for Raikkonen's Ferrari using apparently much more fuel than Fisichella's Mercedes at Spa.
"At the start Raikkonen was using his tyres more aggressively than Fisichella. That costs you a lot of fuel," he said.
"Additionally you don't know how much fuel was still in his (Raikkonen's) tank (at the pitstop). Maybe the Force India was empty and the Ferrari had some left. You also don't know if all the cars are exactly on the (605kg) weight limit."
