Yasa surpasses its own record in motor power density
UK-based electric motor specialist Yasa, part of Mercedes-Benz, has broken its own record for power density. With a short-term peak output of 750 kW, Yasa reports an unofficial new world record for electric motor power density of 59 kW/kg.
Picture of an older Yasa model
Image: Yasa
By Carla Westerheide
22.10.2025 - 11:09
In July, Yasa achieved 550 kW at a weight of 13.1 kg with a prototype of its new axial-flux motor, corresponding to a power density of 42 kW/kg. The latest tests with an even lighter version have “significantly exceeded” this figure, the company states.
The recently tested motor is reportedly slightly lighter at 12.7 kg and exceeds the July peak performance with a short-term output of 750 kW. At 59 kW/kg, the power density is roughly 40 per cent higher than the previous tests.
While the 42 kW/kg figure in July was only shared in a
LinkedIn post by Chief Technology Officer Tim Woolmer rather than through an official company announcement, Yasa has now issued a formal statement, even though the record remains unofficial.
Up to 400 kW continuous power?
Yasa indicates that the current prototype was not developed purely for peak performance. The company estimates that “that all-important continuous power for the new motor will also be in the region of 350kW-400kW.” In summer, Woolmer had mentioned 670 volts and 850 amperes over five seconds, but similar detailed figures for the new record have not been released. “Further details on the development of the prototype motor will be shared in upcoming releases,” Yasa states.
Woolmer had already suggested a new record in July, noting that, together with partner Drive System Design, the test bench had been pushed beyond the initially planned 500 kW limit and that further tests on a “large test bench” would follow in summer. The 750 kW output was reportedly achieved on this larger facility.
“On behalf of the entire YASA team, I’m proud and excited to so quickly follow up on the already remarkable results of our initial testing with this incredible result,” said CTO Woolmer in the announcement. “To achieve a 750kW short-term peak rating and a density of 59kW/kg is a major validation of our next-generation axial flux technology. It’s proof of what focused engineering innovation can achieve. And this isn’t a concept on a screen — it’s running, right now, on the dynos. We’ve built an electric motor that’s significantly more power-dense than anything before it – all with scalable materials and processes. This motor will bring game-changing technology to the high-performance automotive sector.”
“This record demonstrates what makes YASA unique,” added Yasa CEO Jörg Miska. “With three times the performance density of today’s leading radial flux motors, YASA continues to redefine the boundaries of what’s possible in electric motor design – turning pure innovation into tangible engineering progress. Our technology is delivering measurable results today, while paving the way for a new generation of lightweight, efficient electric propulsion systems.”