Fuel Duel

Considering running your car on sustainable fuel? We've dyno tested the first publicly available option to see the effect on power, torque and emissions compared with unleaded petrol

IN JUNE LAST YEAR, FUEL SPECIALIST Coryton launched the first sustainable gasoline to be made publicly available in the UK. Called Sustain Classic Super 80, it's a biofuel with a 98 RON (octane) rating and is certified to deliver an overall greenhouse gas saving of 65 percent compared with fossil fuel. Motorsport has been an early adopter of sustainable fuels and Coryton has created over 400 biofuel formulations for different applications, one of which powered Prodrive's Hunter T1+ to podium places on the 2023 and '24 Dakar rallies.

Coryton is betting on classic car owners being early adopters too; the formulation of Sustain Super 80 is aimed primarily at them. It combines 80 percent sustainable biofuel (hence the name) with 20 percent fossil fuel and less than one percent ethanol. Ethanol is now up to ten percent in regular unleaded (E10) gasoline and remains at five percent in superunleaded (E5) formulas; although it helps lower emissions it attacks nonferrous metals, rubbers and plastics, which are often found in older car fuel delivery systems.

Sustain Classic Super 80 is a drop-in fuel, which means it can replace or be mixed with any pump gasoline. Intrigued to see what effect it would have on power, torque and emissions, we took three of our long-term test cars and dyno tested them on regular pump fuels and then Super 80. This is different from what we did back in issue 306 when we reported on a back-to-back driving comparison of two Mazda MX-5s. In that test, the Coryton sustainable fuel was formulated to match regular E10, 95 RON unleaded, so its sustainable element was supplemented with 10 percent ethanol, as per the pump fuel.