The Department for Transport (DfT) has confirmed that a new type of bio-fuel, known as E10, will become the standard for unleaded petrol as early as August 2021.

E10 petrol is unleaded petrol which contains up to 10 per cent bioethanol, taken from renewable sources such as sugar beet and other vegetable matter. This 5% more bioethanol than regular unleaded which contains up to five per cent ethanol. Fuels with higher bioethanol content produce less CO2 when burned and the DfT estimates that switching to E10 as standard will reduce a car’s CO2 emissions by around two per cent and that overall changing to E10 will cut the UK’s CO2 emissions by 750,000 tonnes a year – equivalent to removing 350,000 cars from the road.

That all sounds great doesn’t it, and for the planet it certainly is but it’s bad news for classic car owners. Actually, it’s not just classic car owners as some models built between 2000 and 2010 are also vulnerable to damage.

Why is this bad?

Increasing the ethanol level in petrol poses two main risks to older cars. The first is that it is a solvent, and it can cause degradation of rubber and plastic components, such as hoses, seals, fuel lines and filters. The second issue is that it also absorbs water from the atmosphere, potentially leading to condensation and corrosion in fuel tanks, lines and other metal components.

The most dangerous risk is that rubber lines will swell and perish and we can think of many classics where the main fuel line to the carburettors inside the engine bay is rubber rather than a hard line – a potentially very dangerous fire hazard. Of course, it will be possible to replace rubber fuel lines with a modern Ethanol resistant product but it’s going to be some time before the right hoses are available for many classic car makes. And of course, getting to those hoses and replacing them can be a time consuming and costly exercise too.

The plan is that E10 will not completely replace E5 overnight and E5 will continue to be sold as super unleaded (98 RON) at forecourts where two grades of petrol are currently sold with a commitment from the DfT to protect the supply of E5 fuel for at least five years.

However, at filling stations with only one grade of petrol, this will become E10 except in remote areas. That means that we may all have to drive to larger stations to be certain of getting E5 and of course it will more expensive as super grade unleaded is currently 136p a litre which is over 13p more expensive than regular petrol.