ESPN looks at how the relationship between Ferrari and Shell changed to squeeze as much performance as possible from every last drop of fuel.

Since the introduction of new engine regulations last year, interest in power units has rocketed in Formula One. Speculation over the relative power outputs of the four manufacturers is a weekly talking point, as Ferrari, Renault and Honda attempt to close the gap to Mercedes at the front.

Ferrari has undoubtedly made the biggest improvement since 2014, with some sources claiming Maranello has matched Brixworth for power this year. The change in Ferrari's engine philosophy ahead of the start of this season has been well documented, as the team reversed its 2014 decision to prioritise packaging over power.

However, there is another key ingredient that should not go unnoticed. Just as Ferrari admitted to getting the balance wrong between the aero advantages of tight packaging and outright power ahead of the introduction of the V6 turbos, technical director James Allison says his team also overlooked the importance of its relationship with fuel and lubricant supplier Shell.

"It's a partnership that, when it works well, is extremely important, especially under these rules," Allison said early this season. "I don't think necessarily Ferrari put as much investment into the relationship as they should have done running into 2014, but the guys at the helm now have really put the effort in there and we are reaping the rewards of that effort. Shell have been playing their part very strongly."

Shell's innovation manager for motorsport, Guy Lovett, says the closer collaboration with Ferrari means the oil giant has become an integral part of Ferrari's pursuit of power.

"James' comments are a fair reflection of what happened and from both sides we've made massive improvements in how we collaborate together," Lovett told ESPN. "If I look back at the last 12 months or 18 months, we are now much, much closer and entirely integrated in the way we are working.

"We have people from our team in Maranello pretty much all the time, completely openly sharing data and information. We have a single performance development plan for the whole year that combines fuel, oil and engine power unit upgrades. With that much more focused collaboration, we are really starting to see the benefits of it now. It's definitely going in the right direction.

"Going from a naturally-aspirated V8 engine to a downsized 1.6-litre turbocharged hybrid system with direct injection - it was a massive change. I think the thing that has really brought a lot more focus - and pressure as well - onto the fuel is the fact that the engine is incredibly responsive to fuel formulation. We've seen that in the past at Shell in any downsized, highly-boosted engine, it's very responsive to what we can do with the fuel.

"On top of that, the F1 regulations now mandate that the drivers can only take on 100kg of fuel alongside the fuel-flow rate limits as well. That is another boundary condition against which we have to develop. We want to try to put as much energy in every single drop of fuel, but also optimise it for power or combustion and efficiency. There are a lot of parameters at play here and some of the good components for energy, for example, are not so good for out and out power, and vice-a-versa.

"So we need to very subtly balance the formulation and that really comes down to understanding. We understand much better now and that comes from the very close collaboration we enjoy with Ferrari."

That close relationship is even more important than in 2014 now that in-season development of the power unit is allowed under the token system. Ferrari spent three tokens worth of upgrades on its internal combustion engine in Canada and Lovett says that also opened opportunities to find performance and cooling gains with the fuel and oil.

"Yes, this year is more challenging, but actually more interesting and rewarding because of the token system and the ability of the teams to continue to develop the power units during the season. It means we are constantly designing and developing against a moving target, but because of the integration we have with Ferrari we can do that together and the development loops are always moving together.

"In the past fuel has been one of the only things you can change in the season, so that bit hasn't changed for us, but what has changed is that the engine is moving as well and that actually presents opportunities as much as anything. The key is to optimise the package as a whole rather than the components in isolation, because when you bring them together they need to be working as a whole." In a normal season Shell looks to bring three to four iterations of fuel and oil to the races and Lovett says each upgrade is a major undertaking that has to ultimately provide results.

"We're not doing it for the hell of it, because it's quite a big effort behind developing, homologating, proving and introducing a new fuel into the race car. For all that effort there needs to some reward, and the reward is ultimately performance. We are looking for a sizable performance gain between each of the fuel and oil iterations we are working on throughout the season."

Shell

The closer collaboration between Shell and Ferrari has also attracted attention from the cockpit. Kimi Raikkonen has never been one to over-emphasise, but he too sees the importance of the closer relationship between team and supplier this year.

"It's all part of the relationship they have had for many years," Raikkonen told ESPN. "It's a big help because Ferrari can produce a great engine, but it's nothing without the fuel and the fuel has to suit the engine, so there is a lot of teamwork to put the things together to get that power and reliability. They cannot just build the engine and the fuel separately, they have to work together to improve in all areas, not just fuel but cooling and elsewhere. It's important for us but it also helps a lot for Shell and road car fuel."

Competition between fuel suppliers is more intense than ever in Formula One, and as with all competitions in sport the only goal is to win. The Shell brand still benefits from the exposure of its long-lasting relationship with Ferrari, but its involvement is about so much more than just a marketing exercise.

"We have around 50 scientists, engineers and analysts working on the F1 programme back at our technical centres around the globe, so it's a big activity for us and we place a lot of value in it," Lovett explains. "Mainly it's about seeing the brand association with the Ferrari brand itself but also it's the technology transfer enabling us to bring the technology and innovation we are working with on Ferrari, extract that from the motorsport application and apply it to the road-going formulations for fuel and oil, like V-Power and Helix. That is one of the fundamental reasons behind us being in Formula One."