11-06-2025 | Posted by Joaquín Martí
This post is partially inspired in an article published by The Economist in April 2025.
In the evolving landscape of electric vehicles (EVs), in-wheel motors (IWMs) are emerging as a transformative technology. By integrating the propulsion system directly into the wheels, this approach offers a radical shift from conventional vehicle architectures—unlocking new possibilities in performance, efficiency, and design.
In-wheel motors are electric machines embedded within the wheel hub or rim. Unlike centralized powertrains that rely on mechanical linkages—such as driveshafts and gearboxes—in-wheel motors apply torque directly to each wheel. This configuration simplifies vehicle systems and allows for independent control of each wheel’s torque, which has significant implications for vehicle dynamics and control.
In addition to being simpler and potentially cheaper to install than conventional, centrally mounted engines, their energy efficiency allows an EV to travel a greater distance on a single charge. The space freed up within the body also allows for more spacious interiors, as well as lighter and more aerodynamic bodies.
Protean Electric, based in England, produces an IWM made up of two concentric rings. One is an electromagnet embedded in a static component (stator); a larger ring (rotor) contains permanent magnets and rotates around the stator. When an alternating electric current is induced in the stator it creates a rotating magnetic field that causes the rotor to spin in sync. Protean’s motors are already being installed in light commercial vehicles converted to run on electricity by Protean’s parent, the BEDEO Group. ConMet, an American company, also fits them to the wheels of lorries where they work in reverse as generators, powering the vehicles’ refrigeration units.
One issue with IWMs is that they can be more vulnerable to shocks and vibrations from the road surface, though Protean says they have tested their IWMs and should last the lifetime of a typical car. Another issue often raised with IWMs is that they increase a vehicle’s unsprung mass, although the effects on handling should be moderate if the unsprung mass is sufficiently smaller than the total mass.
Donut Lab makes IWMs for its Finnish parent, Verge Motorcycles. It has introduced a donut-shaped electric motor that integrates directly into the wheel rim. The company unveiled this technology at CES 2025, showcasing a family of five motor models tailored for various applications, from heavy-duty trucks to drones. The motors deliver exceptional performance, with the most powerful variant producing up to 630 kW and 4,300 Nm of torque, all within a compact 40 kg package. By integrating the motor into the rim, Donut Lab addresses the issue of the unsprung mass, enhancing vehicle handling and ride quality..
DeepDrive, a Munich-based company that makes IWMs for BMW and others, has a design that uses two rotors, one that revolves outside the stator and another inside, to increase the motor’s efficiency. The company reckons that, compared with a traditional EV set-up, their IWM could give an EV some 30% more range in typical driving conditions.
The ring-shaped motors of the Slovenian Elaphe fit inside a wheel leaving enough space for a typical, large brake and caliper fitment suitable to very high-performance vehicles. The gull-winged ItalDesign Quintessenza, first displayed in China, has since been fitted with four Elaphe wheel motors. Elaphe also touts the extreme precision control its motors allow, improving acceleration and braking. Production of some sort is claimed to be coming in the third quarter of 2025.
One way or another, this type of motors may play a role in the future. If you need help on the electromagnetic, mechanical, aerodynamic, manufacturing or other aspects your design, want to experiment with a digital twin, or suspect that a collaborative platform like 3DEXPERIENCE can assist you, Principia’s experts are ready to support you.
