Honda motorsport boss Yasuhisa Arai says progress with fuel development is "levelling off a bit" after early gains with the current power units.
The introduction of the 1.6-litre V6 turbo power units at the start of 2014 also included limitations on fuel flow rates and the total amount of fuel available in a race. Developments in fuel technology have allowed teams to find more power as a result, with Shell claiming to have delivered 25% of Ferrari's power unit improvement in 2015.
Asked if fuel development is still an area of untapped potential, Arai told F1i: “I think so.
"At the start of the fuel development it was a steep improvement curve, but now it’s levelling off a bit. I assume that every other team may have similar issue. Fuel is now very sophisticated, however I’m sure that there is still room for improvement in the future. So we will to continue to make the effort because it is important to keep pushing fuel performance to improve horsepower”
And Arai says Honda maintains a close partnership with fuel supplier Mobil1 which leads to a number of solutions being tested throughout the year.
“[We work] very closely. We discuss with Mobil1 directly. Of course it is one of the big partners but from the R&D side - our R&D and Mobil1’s R&D - we have very big discussions. They made many kinds of fuel which we tested many times to realise what is the best way and the best solution. Day-by-day, every week, every month, we keep doing that.”