Ethanol Remap
Ethanol remap: drive for less
Filling up is becoming more and more expensive. Unleaded 95 and 98 octane are now over €2 per litre. E85, on the other hand, is currently priced at around €0.83 per litre in France. Ethanol remapping is the solution to run your petrol car at this price — with no kit to install, no added parts. Just an intervention on your vehicle's ECU, carried out in less than two hours by an expert from the RS-TRONIC network near you.
20 000+
Customers who switched to remapping
1000€
Average savings/year
What is ethanol remapping?
E85 superethanol is a fuel produced in France from plant-based materials (sugar beet, wheat, corn). It is a renewable fuel, of agricultural origin, locally manufactured, which varies very little according to the price of crude oil.
For a petrol engine to use it, its operation must be adapted. This is precisely what ethanol remapping does: an RS-TRONIC technician intervenes directly on your vehicle's **engine control unit **(the ECU) to teach it how to manage E85. No parts are added, no mechanical modification is carried out. Everything happens in the engine's onboard software.
Once remapped, your vehicle becomes flexfuel: it can run on E85, on petrol, or on both mixed in any proportion, in all circumstances.
Our packages
The two RS-TRONIC ethanol remapping packages
Ethanol E85 remapping (from €490 incl. VAT)
Ethanol E85+ remapping (from €590 incl. VAT)
Our guarantees
The RS-TRONIC guarantees
Certified mappings
Free reset to original for 5 years
Post-intervention check
Follow-up and support
Calculate your E85 ethanol savings
*Savings calculations take into account an average observed extra consumption of 20%.
Why choose remapping over a conversion kit?
There are two ways to switch to E85: install an E85 conversion kit or remap the ECU. These are not equivalent solutions.
The kit is an electronic component that sits between the sensors and the original ECU. It interprets the data in real time and adjusts the injection in an approximate way. It is a generic, non-personalised solution, which doesn't take into account the real specifics of your engine.
RS-TRONIC remapping acts directly within the original ECU. The mapping is written bespoke, tailored to your vehicle, to its real condition, to its engine parameters. The result is more precise, more stable and more powerful, with no additional parts to maintain or replace.
Beyond performance, the price difference between the two solutions is significant. A certified conversion kit costs on average nearly twice as much as an RS-TRONIC remap. This gap radically changes the return-on-investment calculation.
What is Flexfuel?
Drive with peace of mind on unleaded petrol or superethanol
A flexfuel vehicle can use E85, petrol, or any mix of the two in its tank, in any proportion. You fill up with E85 when you find it, you top up with unleaded if needed. The engine adapts automatically.
Priority is always given to E85 whenever it's present in the mix, to maximise your savings. You have nothing to do, nothing to adjust: your vehicle manages everything on its own.
What are the gains with an RS-TRONIC ethanol remap?
Power gain with ethanol
E85 has an octane rating of 105 to 107 RON, well above unleaded 95 (95 RON) and even unleaded 98 (98 RON). In practical terms, the higher the octane rating, the more the fuel resists auto-ignition and allows for better-controlled combustion.
What this means for you behind the wheel: an engine that responds better, smoother driving, improved driving comfort, with no mechanical modification. And for vehicles remapped in E85+, a measurable power gain.
Savings at the pump
As of 11 April 2026, average prices observed in France:
| Fuel | Average price |
|---|---|
| Unleaded 98 | ~€2.05/litre |
| Unleaded 95 / E10 | ~€2.01/litre |
| E85 Cheapest | ~€0.83/litre |
Despite extra consumption of around 20% on E85, savings at each fill-up remain very significant. For a driver covering 15,000 km/year with an average consumption of 7L/100, ethanol remapping can generate up to €1,000 in savings per year.
How does an ethanol remap at RS-TRONIC work?
Vehicle diagnostic
ECU remapping
Validation and road testing
A 3-step intervention, carried out by an RS-TRONIC expert
Every ethanol conversion is carried out in an approved centre, by a technician trained and certified by RS-TRONIC. From reading the original ECU to road testing, nothing is left to chance.
The RS-TRONIC network: experts near you
RS-TRONIC is over 80 dealers in France, spread across the entire country. Each dealer is a professional trained on the latest generation of remapping tools, selected and certified by RS-TRONIC. Vous bénéficiez de l'expertise d'un réseau spécialisé, avec des tarifs au plus juste et une intervention rapide, généralement en moins de deux heures.
FAQ
Frequently asked questions
No. Engine ECU remapping is a technical operation that requires professional tools and in-depth expertise. A poorly executed mapping can lead to malfunctions or even engine failure. It is essential to entrust this intervention to a certified technician from the RS-TRONIC network.
None, when carried out correctly by a professional. A common misconception persists: that ethanol would damage the engine and its peripherals faster. This is false. Since the 1999 decree and the introduction of E5 petrol blended with ethanol, all vehicles manufactured since that date have been designed to accept E85 in the fuel system. E85 burns more cleanly, generating fewer deposits in the engine. Risks only exist in the case of a botched or unsuitable mapping, which doesn't happen within the RS-TRONIC network.
No. Ethanol remapping is reserved for petrol and petrol hybrid vehicles. For diesel vehicles, RS-TRONIC offers Stage 1 engine remapping, which can generate savings of up to 1 litre per 100 km at equal driving style.
A large number of vehicles currently on the road are compatible. As a general rule, petrol vehicles registered after 2001 and meeting the Euro 3 standard are eligible. To find out if your car can be remapped, use our online compatibility configurator.
On the insurance side, no specific procedure is currently in place regarding engine remapping. We nevertheless recommend that you contact your insurer to check the conditions of your policy.
Ethanol vaporises less well in cold weather, which can make starts slightly more difficult below -10°C. Two things matter to avoid this: a mapping developed to operate optimally in all seasons (which is the case at RS-TRONIC) and an ignition system in good condition, including spark plugs and coils. E85 requires a stronger spark than petrol and worn spark plugs can be enough to cause issues. If needed, adding a few litres of petrol to the tank in winter solves the issue immediately.