For in this modern turbo hybrid era, where performance is as much the responsibility of a fuel supplier as it is an engine manufacturer, McLaren and Honda's partner ExxonMobil think there is scope for some healthy gains in the short term, even without major design tweaks.

Horsepower boost

After a 10-15bhp power lift was delivered with new fuels and lubricants for the final pre-season Barcelona test, there is talk that similar steps are on the cards for 2016.

In an exclusive interview with Motorsport.com, ExxonMobil's motorsport technology manager Bruce Crawley says he senses good opportunities for progress with the relationship with Honda still in its early stages.

"Theoretically there are still some big gains to be had: both in terms of fuel, on the combustion side, and also on the friction side, on the engine as well," he said.

"In the development process we are a little behind because the programme started later than our rivals, so you might expect us to be making more progress. But certainly we are working on it right now.

"We are looking from a friction perspective, improving the efficiency of the engine by taking friction out. We've already identified that there are some gains to be had there: so it is just getting that in to the system."

Working in unison

The new hybrid regulations, which include a fuel flow and 100kg race limit, have meant that engine manufacturers and fuel suppliers have to work closer than ever.

The forges between Shell/Ferrari and Petronas/Mercedes have been key to their development, and the same is true of ExxonMobil and Honda – who both know that success relies on them working together.

"The level of interaction is very, very intensive," added Crawley. "It is a systems engineering approach. It isn't a question of the two companies working in isolation so that we come up with an idea and they come up with an idea. It is really an integrated way of working.

"The combination of the combustion chamber design and the operation of the engine with the fuel chemistry – if you get that right, you can get some significant performance gains."

Canada plan

Crawley says that proof of the kind of leaps that can be made came for the second Barcelona test, when ExxonMobil introduced its current specification of fuel.

"The fuel we are running right now, which went in to the car in Barcelona – at the second test – that was a double digit improvement in horsepower," he said. "It was a significant improvement.

"That is coming from a combination of engine design and combustion system design and fuel. So the programme, really, is to try to get as much performance out of this engine – improve the thermal efficiency of this engine.

"We have ideas about how that should be done from a chemistry point of view and also a design point of view, and so do Honda.

"And I think we have made some really good headway now – you can see it coming through. The performance is coming, the energy recovery side has improved quite significantly.

"If you look at fuel development right now, we are targeting our next fuel upgrade for Montreal – that is our target. Whether that happens or not I don't know, but we expect it. And then there will be another one coming through later. It's continuous improvement."

Low hanging fruit

Crawley says that the partnership has to work both ways, with ExxonMobil not only being able to deliver better products, but Honda providing hardware that allows the fuel scope to shine.

"What we are pushing on the engine side is for them to give us a head room of performance to allow us to improve the fuel within that: so it is sort of an iterative process.

"So for example, we close that area down from a knock point of view, but you need to open that up to give us more room to nibble in to that area."

He added: "If you look at our previous relationship [with Mercedes], that was for nearly 20 years, so you can pick up the phone, you know the person: the level of interaction is far greater, the level of understanding is much greater. We are still in a little bit of a honeymoon period!

"The closer and longer you work with people, the more effective it is. There are gains to be had from that aspect and also the fact that we are at a different stage of our development to others – so low hanging fruit is available at the beginning of the development programme. After that it becomes harder and harder."

New technology

But it is not just with better fuels or design iterations where ExxonMobil and Honda are concentrating, for Crawley suggests they are looking at all-new technologies in the near future too.

Most recently there has been talk of Homogeneous Charge Compression Ignition [HCCI] and jet ignition technology changing the battle ground in F1.

"There is some interesting technology around," explains Crawley, without specifying in exactly what areas they are looking. "So, there are definitely different ways of approaching that – and ignition is important.

"There is an awful lot of work going on in this area, and I think there is technology that is already patented, but it has to fit in what you are trying to achieve.

"If you look at the over-arching fundamental target, which is to improve thermal efficiency, then anything that is going to enable you to do that you are going to look at."

The push for improvement is far from its end yet.