From September 2021, regular unleaded petrol will transition from ‘E5’ to ‘E10’. E10 petrol contains up to 10% renewable ethanol and its introduction is aimed to help reduce CO2 emissions and tackle climate change. E5 petrol contains up to 5% renewable ethanol.
There is a lot of concern in the classic and specialist sport car world as to the impact of E10 petrol, but in reality, E10 petrol is already widely used around the world, including across Europe, the US and Japan. It has also been the reference fuel against which new cars are tested for emissions since 2016.
All Caterham Sevens since 2006 have been powered by either Ford derived engines or, in the case of the Seven 160 only, a Suzuki engine. The engines in all generations of these products are compatible with E10 petrol.
For all other Caterhams; powered by Rover k-series, Vauxhall or Ford x/flow engines; we recommend using super-unleaded, which remains as E5 petrol.
The corrosive properties of the bioethanol in E10 petrol may adversely affect fuel hoses (the main fuel lines themselves are copper and will not be affected) and your dealer will check these during routine servicing. Owners that look after the car themselves are recommended to pay close attention to fuel system components and if there are any signs of deterioration, replace with the latest specification of part.
One of the concerns with E10 petrol in specialist and classic cars is its hygroscopic property, meaning it attracts water, absorbing it out of the atmosphere, causing the fuel to separate if left for long periods in the tank (which can cause internal corrosion to the tank and may make the car difficult to start). In practice, it is felt that this risk is small, but if leaving your Seven unused for extended periods, such as over winter, you may wish to consider using super-unleaded petrol for the last fill-up prior to putting it away, regardless of age.
For a specialist manufacturer like Caterham, confirming the suitability of every component in the fuel system for a fuel that has not been required as part of individual or low-volume type approval until recently is a significant task. Ongoing testing is required and where possible, we hope to confirm the suitability of E10 petrol more widely to the owners of older Sevens in due course.
The E5 and E10 symbols are clearly displayed on the petrol pump when purchasing fuel.