Synthetic fuels, also called e-fuels when produced from electricity, are being explored by several car manufacturers as a potential solution to extend the life of internal combustion engines while reducing their CO₂ emissions. Companies such as Bosch, Porsche, and Stellantis are particularly interested in this technology, which would allow existing cars to run without modifying their engines and future models without large batteries. However, the production process is energy-intensive, costly, and limited in volume, raising questions about the feasibility of this approach. Synthetic fuels are produced through a process that involves obtaining hydrogen via the electrolysis of water, which requires a significant amount of electricity (ideally green energy). This hydrogen is then combined with CO₂ captured from the atmosphere or biogenic sources to produce methanol, which can be transformed into liquid hydrocarbons. Porsche has described this process in detail on its website. The interest in this technology lies in its compatibility with existing internal combustion engines, potentially allowing for a reduction in the carbon footprint of certain cars without requiring owners to replace them with electric models. However, the climate benefit depends on the production conditions, the origin of the electricity, and the carbon used. Even if the carbon used to produce the fuel is captured upstream, its combustion always releases CO₂ to the exhaust. Several players in the sector are promoting this approach. Bosch, a German automotive supplier, believes that renewable synthetic fuels should be part of the solutions to reduce transport emissions. Thomas Pauer, president of the Power Solutions division of Bosch, stated in May 2025 that it is the only way to achieve climate goals in the transport sector. The company is also developing its Digital Fuel Twin system, intended to trace the quantities and characteristics of the fuels used by vehicles. At Porsche, e-fuels are part of a strategy that aims to have several types of engines coexist. The manufacturer, which supports the development of these fuels and participates in the pilot project Haru Oni in Chile, sees them as a way to continue using internal combustion engines with a reduced carbon footprint. Michael Steiner, a member of Porsche's board of directors in charge of development, noted that e-fuels complement the company's strategy of diversifying its range of engine types. Stellantis has also explored this possibility. In April 2023, the group announced that it had tested the compatibility of e-fuels with 28 families of gasoline and diesel engines. It estimated that these fuels could potentially reduce up to 90% of CO₂ emissions on the considered cycle and allow 28 million of its vehicles to circulate in Europe. Carlos Tavares, then general director of the group, described this approach as "a new tool in the fight against climate change, with a potential impact in the very short term." However, these figures are estimates and not guaranteed reductions for each vehicle. Transport & Environment France, a European campaign group for clean transport, has raised concerns about the credibility of synthetic fuels as a solution for massively decarbonizing private cars. According to a study commissioned by them to the Ionect firm and published in April 2026, the production cost of synthetic gasoline could reach approximately 4 euros per liter in 2030, leading to a price at the pump close to 7 euros per liter. These amounts are projections and not yet observed prices at the pump. The production process largely explains this gap. Producing decarbonized hydrogen requires a large amount of electricity, and the synthesis and transformation steps of the fuel add to the cost. In contrast, an electric car directly uses the electricity stored in its battery to power its engine, and refining oil requires four times less effort, for a production cost of about 1 euro per liter. Nicolas Raffin, spokesperson for T&E France, noted that this difference in efficiency constitutes a major obstacle: "With comparable amounts of electricity, the electric route allows traveling more kilometers than going through the production of a synthetic fuel and then its combustion in an engine." The second difficulty concerns the available volumes. According to estimates by T&E France, about one million tons of synthetic fuels could be available for the automotive industry by 2035, with the majority of the production destined for aviation, a sector much more difficult to electrify. This would represent only about 3% of the fuel supply needs of the automotive fleet in the scenario considered by the association. Even with favorable assumptions, the quantities would remain very insufficient to replace a significant part of fossil fuels consumed by cars. For T&E France, synthetic fuels should be reserved in priority for sectors where replacement solutions are more limited, notably aviation and maritime transport. The production of fuels intended for aviation can also generate fractions or by-products that can supply other sectors, such as the chemical industry or certain road uses. However, this does not justify making the automotive industry a priority when an electric alternative already exists for private cars. "E-fuels could find their place in specific uses, for example for certain sports or luxury cars, but not on a large scale," declares Nicolas Raffin. Even if e-fuel technology can still evolve, like batteries for electric cars, synthetic fuels do not seem to be a real solution for the automotive market, but rather a beautiful mirage full of promises for T&E France, especially since there is an urgent need to green our automotive fleet. "When we see the climate changes in our country, notably this summer, we realize that we need immediate decarbonization," concludes Nicolas Raffin. And compared to the electric car, at the present time, synthetic fuels are not competitive enough.