The Mercedes-Benz Actros — Daimler’s best-selling heavy truck, with more than 1.5 million units sold since 1996 — is about to gain an unusual new powertrain. Under a partnership announced by Daimler Truck, the Munich engineering specialist KEYOU will convert the Actros to run on hydrogen combustion, with vehicles offered to customers from the end of 2027.
The conversion keeps almost all of the familiar diesel hardware. KEYOU takes the 12.8-litre OM 471 engine that powers the standard Actros and re-engineers it to burn hydrogen instead of diesel, leaving roughly 80% of the original engine untouched. The result, badged the KEYOU HICE.40, is a 4×2 tractor unit rated for 40 tonnes, producing up to 350 kW and carrying compressed hydrogen at 350 bar for a claimed range of up to 650 km. Daimler supplies the Actros L 1848 units and OM 471 engines from its Mannheim plant; KEYOU handles the conversion — an arrangement Daimler describes as “partnership instead of in-house development”.
The engine was never the problem
For the Swiss Power-to-X Collaborative Innovation Network (SPIN), the interesting part is not the engine — it is what the engine is allowed to burn. A hydrogen combustion engine works much like a diesel: it ignites fuel in cylinders and turns a crankshaft. What it does not do is release fossil carbon. This is the point we keep returning to: the problem was never combustion, it was fossil carbon. Remove the fossil carbon from the fuel, and the combustion engine stops being a climate liability.
That reframing matters because it widens the toolbox for defossilising heavy transport. Battery-electric drivetrains and hydrogen fuel cells are not the only zero-carbon options on the table; an internal combustion engine fed with green hydrogen belongs in the same category.
Why this is a Power-to-X story
A hydrogen combustion truck is only as clean as the hydrogen in its tank. Fill it with fossil-derived “grey” hydrogen and the climate benefit largely evaporates; fill it with green hydrogen produced by electrolysis from renewable electricity, and the truck becomes genuinely fossil-free. Every hydrogen combustion fleet that reaches the road is, in effect, new demand for renewable hydrogen — exactly the kind of offtake the Power-to-X build-out needs in order to scale.
KEYOU is no newcomer
Founded in 2015 by three former BMW powertrain engineers, the independently owned company has specialised in converting diesel engines to hydrogen ever since, claiming a world-record combustion efficiency of 44.5% back in 2018. It secured TÜV Süd road certification for an 18-tonne hydrogen truck in 2023 and has built hydrogen engines for partners including Komatsu and Volvo Trucks. The Actros conversion will be carried out with Bücker + Essing, part of the Elevion Group, and the trucks qualify for Germany’s federal hydrogen funding — with leasing and an “H2 Mobility as a Service” package offered alongside renewable-energy firm GP Joule.
A crowded field
Daimler and KEYOU are not alone. MAN began delivering in-house hydrogen combustion trucks in late 2025 — an initial run of around 200 units across Germany, the Netherlands, Norway and Iceland — using 700-bar storage and a 383 kW engine. Volvo Trucks started road-testing its own hydrogen combustion truck this year, and Cummins has validated the technology at both 6.7- and 15-litre displacements. With the KEYOU conversion, the Actros platform alone will soon offer three zero-emission options: battery-electric, the NextGenH2 fuel-cell truck, and hydrogen combustion.
The regulatory tailwind is real. The EU’s CO₂ standards for heavy-duty vehicles tighten sharply from 2030, and trucks emitting less than 3 grams of CO₂ per tonne-kilometre count as zero-emission — the same status granted to battery-electric and fuel-cell vehicles. Hydrogen combustion clears that bar.
The same question, every time
The lesson SPIN draws from announcements like this is consistent: technology neutrality, anchored to a single non-negotiable principle. Whether the molecule is hydrogen burned in a piston engine, e-methanol in a ship, or synthetic kerosene in a jet, the question is always the same — where does the carbon come from? Answer it correctly, and even the humble combustion engine has a fossil-free future.
Power-to-X Congress Switzerland 2026
«Reality Check with Net Zero» — 22 September 2026, 10:00–18:00, Kursaal Bern.
Co-organised by energie-cluster.ch and the Swiss Power-to-X Collaborative Innovation Network (SPIN), in partnership with Réseau H2 Suisse Romande.