Williams hoping to find F1 fuel gains over Mercedes

While Mercedes uses Petronas products in its engines, Williams has a long-term plan to switch to Petrobras.

Williams technical chief Pat Symonds said the difference in suppliers would give his team the possibility of getting an edge now that fuel technology had become a key battleground under the turbocharged V6 hybrid engine rules.

Asked by AUTOSPORT if there was a danger that Mercedes would naturally make its engine more suited to Petronas, Symonds replied: "We're working on developing the fuel. Naturally we want the fuel to be good.

"There's no reason theoretically why Petrobras can't develop a better fuel than Petronas, so it can be a positive, an advantage.

"We're not there yet, but that's what we're working towards."

Symonds believes there is still a lot of potential to find more performance through fuel development.

"That's not my area of expertise but I know there's a lot more in the fuels now than in the last years of the V8s, where they had reached a limit where it was difficult to find much more," he said.

"But there's still things to be found in the fuels."

He added that this year's Mercedes engine was larger than the 2014 version, but this had not caused any packaging problems.

"The engine's slightly more bulky this year, and the exhausts are more bulky," Symonds said.

"Mercedes went very tight on the exhausts last year but we didn't feel that there was an aerodynamic gain from that so we really don't mind that they're a bit more bulky.

"Everyone's had to accommodate the variable trumpets."