The new spec, created at the company's US R&D base and tested on Honda's dynos in Japan and the UK, is the first upgrade since the start of this season, when the fuel company made a big step relative to last year.

"We're bringing a new fuel to Canada, which we've been working on with Honda," ExxonMobil's global motorsport technology manager Bruce Crawley told Motorsport.com.

"It's a new concept, and quite different to what everybody else is doing. It's part of an ongoing programme of development which is now in its third year.

"We made a significant step forward in Melbourne, with a double-digit power performance increase relative to where the engine was with the previous fuel. We've been running with that fuel so far this season. The new fuel for Montreal represents about a 1 percent power increase.

"In round numbers, that's around 5kW, or about a tenth of a second, depending on what circuit you are on."

Crawley says that the latest fuel spec will give Honda's and the fuel company's scientists and engineers additional scope to collaboratively develop power unit technology and output.

"The interesting thing about this technology we're putting into the engine spec for Montreal is it's very much an enabling technology.

"The fuel technology has the potential, with changes and evolution of the engine hardware, to extract even more performance.

"We very much see this as a breakthrough in terms of enabling further gains with changes to the combustion system of the engine. Basically what we're trying to do is give Honda a headroom space to develop into."

ExxonMobil anticipates making at least two further steps this season: "We're more than half way through our development programme for 2016, and we're expecting another two fuels to come in. We've already identified the fuel for the next upgrade, and then we'll have another one later in the season as well.

"The development programme is more intense again than it was last year. Last year we did four fuels, and this year we expect to do at least four.

"However, the steps that we are making are bigger, and also there's a lot of activity for 2017. There's much more work going on as the programme builds.

"The spec is very specific and tailored to the engine hardware and the mapping. Everything has to synch-up in terms of extracting maximum performance, so you have to map the engine to get the performance out of the fuel.

"So we do generally try to put a new fuel upgrade in at the same time as a major hardware spec change, but not always."

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