YASA, a specialist in axial flux electric motors, has announced a technological milestone with the development of a prototype in-wheel electric powertrain system. The in-wheel system is powered by an advanced motor that recently set an unofficial world record for power density.
“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’s founder and CTO. “This concept technology breakthrough is compact, powerful and light enough to be positioned inside the wheel of an EV, and it is the world’s first mass-neutral in-wheel motor, enabling up to 750 kW (>1,000 bhp) per wheel.
“Combined with a new YASA-developed inverter, it results in a fully integrated prototype in-wheel electric vehicle powertrain, which will bring about a step change in weight reduction, performance and efficiency,” added Woolmer.
The prototype motor, weighing just 12.7 kg, achieved a peak output of 750 kW during recent testing, setting an unofficial record of 59 kW/kg for power density. It can also deliver continuous power between 350 kW and 400 kW (469–536 bhp). Paired with YASA’s next-generation dual inverter – a 15 kg unit capable of 1,500 kW and 100 kW/kg – the system pushes power electronics beyond current benchmarks of 50–70 kW/kg.
According to YASA, the powertrain offers significant benefits for future EVs. Its high regenerative capability could allow manufacturers to downsize or even eliminate rear brakes in certain architectures, removing discs and driveshafts and saving around 200 kg in components, with up to 500 kg possible in ground-up designs. The technology also promises improved energy recovery, potentially boosting EV range.
“Thanks to its exceptional regenerative capability, this system has the potential to dramatically downsize rear brakes on an EV – or even remove them entirely in certain architectures. And by capturing a much greater proportion of regenerative braking energy, this technology can also deliver a significant increase in EV range,” explained Simon Odling, YASA’s chief of new technology.
“What’s more, our new in-wheel motor powertrain not only enables significantly lighter, more efficient and higher performance EVs, but also creates space within the architecture of an EV, giving car makers unprecedented freedom to redesign and optimise packaging, aerodynamics and kinematics,” added Odling.
The in-wheel system is designed to be scalable, supporting outputs from 750 kW for hypercars, to lower power levels for performance EVs. Development of the prototype has been supported by the UK’s Advanced Propulsion Centre, and further details are expected in 2026.
