Ethanol conversion kits: what drivers in France need to know

An offer by supermarket giant E.Leclerc to install ethanol conversion kits from €690 -around €100 cheaper than most competitors - is likely to attract renewed interest as petrol prices continue to rise.

The kits, available across its network of 126 E.Leclerc auto centres, can in principle be fitted to most petrol-engine cars sold since 2000. Once installed, they allow vehicles to run on E85 fuel, which contains up to 85% ethanol.

The installation process takes roughly half a day. According to tests by independent French motoring journalists, the cost of fitting the conversion kit is typically recovered after around 25,000km of driving.

Currently, only around 400,000 vehicles in France run on E85, out of nearly 30 million vehicles on the road.

Because ethanol is less energy-dense than petrol, E85 use can increase fuel consumption by up to 25%. However, it is significantly cheaper at the pump. 

E85 generally costs between €0.70 and €0.85 per litre, compared with more than €2 per litre for petrol since the conflict in the Middle East drove prices up.

Ethanol is produced from agricultural sources – in Europe mainly sugar beet and sometimes grape by-products – and can reduce CO₂ emissions by up to 80%. It also reduces particulate pollution, which is linked to respiratory disease and certain cancers.

Mixing bioethanol with petrol without a certified conversion kit can cause serious mechanical damage, especially in older vehicles. It is also illegal if the vehicle registration does not specify biofuel compatibility, and can invalidate insurance in the event of a claim.

To be officially recognised, conversion kits must be government-approved, installed by a certified professional, and accompanied by an installation certificate. Without this, the modification is not considered compliant.

After installation, the vehicle registration document (carte grise) must be updated. The fuel type code in section P.3 is changed: ES (essence) becomes FE (petrol + E85 dual-fuel), EE becomes FL for hybrids, and FG is used for LPG-capable vehicles. In many regions, the update is free or low-cost.

The technology is not new. In Brazil, ethanol from sugar cane has been widely used as a primary fuel for around 50 years. In parts of the United States, ethanol from maize is also commonly blended into fuel.

However, French manufacturers including Peugeot, Citroën and Renault warn that using E85 conversion kits may void warranties.

Ethanol conversion kits and car warranties

A Renault spokesperson told The Connexion: “The installation of a box, not foreseen when the engine was designed, might have an impact on the functioning and lifespan of engines.

“The Renault group, like all members of the Association des Constructeurs Européens d’Automobiles (ACEA), considers that ethanol conversion boxes carry risks.

“The technical modifications mean manufacturers’ warranties will not apply in case of breakdown.”

Since 2000, all petrol-engined cars have used electronic fuel injection systems. Conversion kits use sensors to detect whether petrol or ethanol is being used, adjusting ignition timing accordingly to compensate for differences in fuel properties.

E85 can also be used in carburettor engines, provided seals are compatible with ethanol. In such engines, ignition timing is often adjusted to optimise performance, as ethanol’s higher octane rating reduces the risk of engine knock.

Three conversion kit manufacturers are currently officially certified in France. Until recently, installation was mainly carried out by fast-fit tyre and brake chains, but E.Leclerc has now entered the market using kits supplied by French firm Biomotors, which are state-certified.

Around 46% of petrol stations in France now offer E85 fuel. Locations can be found via an app provided by the trade body Bioéthanol France.