Record-breaking compact electric motor enables mass-neutral in-wheel powertrain delivering over 1,000 horsepower per wheel
Yasa has developed a prototype in-wheel electric powertrain system built around a motor that recently achieved an unofficial world record for power density, potentially transforming how electric vehicles are designed and manufactured.
The British company’s breakthrough centers on an ultra-compact 12.7-kilogram electric motor that delivered 750 kilowatts of peak power during testing – equivalent to over 1,000 horsepower per wheel. With a power density of 59 kilowatts per kilogram, the motor significantly exceeds current industry benchmarks while maintaining continuous output between 350 and 400 kilowatts.
“In-wheel motors are the major challenge and opportunity for EVs, but until now, technology has been too heavy, limited in torque and not powerful enough,” said Tim Woolmer, Yasa founder and chief technology officer. The new system is compact and light enough to fit inside vehicle wheels while remaining ‘mass-neutral’ – meaning it adds no net weight to the vehicle.
Yasa paired the motor with a 15-kilogram dual inverter delivering 100 kilowatts per kilogram, surpassing typical power electronics that achieve 50 to 70 kilowatts per kilogram. Together, the integrated powertrain enables performance capabilities previously unattainable in in-wheel configurations.
The system’s regenerative braking performance could eliminate or substantially reduce rear brake components, removing disc brakes and driveshafts. Yasa estimates this could save approximately 200 kilograms in conventional conversions, with potential savings reaching 500 kilograms in vehicles designed from the ground up around the technology.
Beyond weight reduction, the enhanced regenerative capability captures more braking energy, potentially extending vehicle range. The in-wheel configuration also frees interior space, giving manufacturers greater flexibility in vehicle packaging, aerodynamics, and design.
While the 750-kilowatt output suits high-performance applications, Yasa plans to offer scalable versions for various vehicle segments. A fully functional prototype is currently undergoing development with support from the UK’s Advanced Propulsion Centre.
“Our revolutionary technology addresses the challenges of current existing in-wheel motor systems,” said Joerg Miska, Yasa CEO. “It is the gateway to lighter, more efficient and higher performance electric vehicles.”
