On June 9, 2026, Mercedes-Benz started what it calls large-scale production of an electric axial flux motor at its Berlin-Marienfelde plant. The number that matters is not the horsepower. It is this: 35 of the 98 process steps on that line are described as new worldwide, backed by more than 30 patent applications. A third of the manufacturing process had to be invented to build a motor whose physics has been understood for decades. That gap, between a theory everyone knew and a line nobody could run, is the whole story.

The spec sheet was never the bottleneck

Axial flux machines are not new. They have shipped in motorsport, aerospace, and low-volume specialty builds for years. What nobody had pulled off was running one down a real automotive line at volume, with the yield and repeatability a series production car demands.

I do not build motors. But I have spent enough years watching impressive lab demos die somewhere between the prototype bench and a production line to recognize the shape of this announcement. The hard problem is almost never the peak number you can hit once, by hand, under ideal conditions. It is hitting a good-enough number twice, identically, ten thousand times, with a process a normally-skilled operator can run on a Tuesday. June 9 is the date Mercedes is claiming it crossed that line. Read it as a manufacturing-engineering result dressed up as a horsepower story.

The Berlin programme spans 30,000 square metres, three halls, and seven production lines, per the Mercedes-Benz Group production newsroom. Seven lines is the tell. You do not stand up seven lines for a halo part you build a few hundred times a year. That is a bet on volume.

Why the geometry is worth the trouble

For a decade the EV drivetrain has been a solved-enough problem. Radial flux permanent-magnet motors route magnetic flux perpendicular to the shaft, land at roughly 3 to 5 kW/kg in production trim per industry comparisons from Traxial and others, and cost little enough to scale. The package is fat and long because it needs a lot of iron and copper. When the battery pack and the software were the hard parts, that was an acceptable tax.

Axial flux changes the routing. Flux runs parallel to the shaft through a flat, disc-shaped stator, which gives you far more air-gap surface area in a much shorter package. The same sources put axial designs at roughly four times the power density of radial, and 30 to 40 percent higher torque density at equal mass.

The concrete comparison is the one to hold onto. In July 2025, YASA, the British axial flux specialist Mercedes-Benz bought outright in 2021, showed a prototype rated at 550 kW (738 hp) weighing 13.1 kg. That is 42 kW/kg, which YASA claimed was the highest power density ever recorded. Set it against a state-of-the-art Lucid radial unit at 500 kW and 31.4 kg, about 16 kW/kg. This is not a 10 percent efficiency win you argue about in a spreadsheet. A motor that does the same work in less than half the mass frees axle weight, floor space, and packaging room that a designer can spend on range, crash structure, or a second motor.

The motor debuts in the new Mercedes-AMG GT 4-Door Coupe. Per ArenaEV's reporting on the launch, the front-axle unit is just under 9 cm wide, each rear-axle unit around 8 cm, and they spin past 15,000 rpm. A drive motor narrower than a paperback is the kind of packaging freedom that quietly rewrites where everything else in the car can go.

The real moat is the air gap

So why has every automaker not switched already? The same reason Mercedes needed 35 new process steps. Axial flux is brutally hard to manufacture, and the difficulty is specific and physical, not a matter of tooling budget.

The air gap between rotor and stator is small, and it has to stay uniform around the entire disc. Let it drift and you get torque ripple, acoustic noise, and accelerated wear, per Traxial's teardown of the manufacturing problem. The topology that delivers the headline power density, a yokeless single stator sandwiched between dual rotors, is exactly the topology that resists cheap, repeatable assembly. The forces trying to pull those rotors toward the stator are enormous, and the tolerance window you have to hold them in is tiny.

When Mercedes says it is running seven lines at volume, the real claim underneath is that it has turned sub-millimetre air-gap control into a repeatable industrial process rather than a hand-built motorsport ritual. If that holds, it is the moat. A motor design patent is easy to route around. A patent portfolio plus a working high-yield line is a different kind of barrier, because the line is the part nobody can copy from a datasheet.

What the headline number hides

Two things temper the excitement, and both get buried under the 738 hp figure.

First, cost and supply. Industry breakdowns put rare-earth permanent magnets at 30 to 40 percent of total motor manufacturing cost. Axial flux does not escape that exposure, it deepens it. Higher power density per motor tends to mean more magnet intensity per vehicle, not less, which points straight back at the neodymium and dysprosium supply chain everyone is already nervous about. The axial-flux-specific component ecosystem is also still thin, which works against the economies of scale that make a technology cheap.

Second, heat. This is the quiet problem. In a dual-rotor design the intermediate stator sits in the middle with very little mass to absorb heat, so high specific power arrives with a serious cooling burden. A motor that is spectacular for 30 seconds on a dyno and thermally throttled in sustained real-world load is a different product from one that holds its rating. The production numbers will tell that story, and they will land below the 42 kW/kg lab prototype.

The counterpoint: one car is not a category

Here is the case for tapping the brakes. This is one motor, in one expensive AMG, from a manufacturer that owns the supplier and therefore has every incentive to frame the launch as a watershed. "Large-scale production" is Mercedes' phrase, and large-scale relative to a low-volume specialty motor is not the same as a Tesla-grade output running into the hundreds of thousands.

The technology becomes a real category shift only when a tier-one supplier, not a captive subsidiary feeding one brand, demonstrates a high-yield axial flux line at a mainstream price point. Until then, treat Berlin as strong evidence that the manufacturing problem is solvable, not proof that it is solved at scale or at a price the mass market will pay. The honest read is that Mercedes has shown the door can be opened, not that everyone is about to walk through it.

What to watch over the next 18 months

Concrete signals, each tied to a number above, in the order they will tell you something.

  • Watch the date, not the dyno. The signal that matters is "large-scale production on seven lines," not "738 hp." Track the first independent yield and warranty data out of Berlin over the next 12 months. A high-power-density motor that fails on air-gap consistency at volume is a recall, not a revolution, and warranty claims are where that shows up first.
  • Benchmark against 16, not 42. When real AMG production output gets published, compare it to the 16 kW/kg Lucid radial unit, not the 42 kW/kg lab prototype. If the shipping motor clears roughly 2x the best radial design, the packaging advantage is real enough to start reshaping how cars are laid out. If it lands near radial, the story was mostly marketing.
  • Model magnet intensity upward. If you are forecasting EV cost or supply risk for 2027 and beyond, assume axial flux raises rare-earth magnet demand per vehicle, given magnets at 30 to 40 percent of motor cost, until magnet-light or ferrite designs actually ship. Do not pencil in a cost reduction that the magnet bill of materials will not support.
  • Track the second line, not the first design. Mercedes owns YASA, so a rival needs either its own line or a merchant supplier like Traxial or Equipmake that has cracked design-for-manufacture. The trigger to watch for is the first tier-one supplier announcing volume axial flux production at a mainstream price. That announcement, not this one, is when axial flux stops being AMG halo tech and becomes a default drivetrain option.

Sources

  • https://group.mercedes-benz.com/company/production/news/axial-flux-motor-berlin.html
  • https://www.arenaev.com/mercedesbenz_rewrites_rules_with_axial_flux_motors-news-5959.php
  • https://traxial.com/blog/why-arent-all-electric-vehicle-motors-axial-flux-yet/