Examining Tesla's Rare-Earth-Free Motor Claim: Supply Chain Holds Firm

In September 2026, Tesla Chief Executive Officer Elon Musk said that the drive motor for the robotaxi Cybercab maintained driving range without using rare earths. It was also reported that the volume of the electric drive unit was reduced by 18% and its weight by 25%. Amid continued procurement uncertainty over rare-earth magnets in the automotive industry, the announcement gave the impression that going rare-earth-free had simultaneously achieved downsizing and weight reduction.

According to reporting by Automotive Business Review on Huxiu, these figures remain unilateral claims by the company and lack backing from independent comparative testing. The specifications of the comparison baseline, the torque-speed relationship, efficiency and temperature rise under continuous operation, and noise — conditions essential for evaluation — have not been disclosed. Its position is that superiority in materials technology cannot be judged from reductions in volume and weight alone.

Tesla announced in 2026 that its motor for the robotaxi Cybercab uses no rare earths, maintaining driving range while making the electric drive unit smaller and lighter. However, Automotive Business Review noted that this is merely a unilateral performance claim by the company and has not been demonstrated by independent comparative testing.

This article organizes the facts within the scope of publicly available information, and examines the current state and limits of motor technologies that do not depend on rare earths, how to interpret performance indicators, and the structure of the supply chain.

Challenges in Verifying Tesla’s

Rare-Earth-Free Motor Claim

What drew attention in Musk’s remarks was the combination of no rare-earth use, maintained driving range, and an 18% reduction in volume and 25% reduction in weight for the electric drive unit. It should be noted that all of these are presented as figures for the vehicle or the system as a whole. The electric drive unit may include not only the motor itself but also the housing, cooling system, reduction gear, and controller. Without clarity on the scope in which volume and weight were measured, and whether the comparison matched output and torque conditions, it cannot be concluded that the change in magnet material directly led to downsizing and weight reduction.

Driving range is likewise a composite indicator. Battery capacity, vehicle weight, aerodynamic drag, tire rolling resistance, and drive efficiency interact with each other. Changes in motor efficiency alone cannot be back-calculated from maintained range. Huxiu’s Automotive Business Review reporting, citing the lack of these preconditions, positions the announcement as not yet at the stage to be treated as a technical breakthrough. While taking the company’s figures as a starting point, evaluation should be withheld until measurements under identical conditions by a third party are published.

Tesla had indicated in 2023 a plan for next-generation rare-earth-free permanent-magnet motors. From outside, there is speculation that Cybercab is an extension of that plan, but the actual configuration and materials have not been disclosed. It is important not to confuse speculation with fact and to clearly distinguish the lack of disclosed information.

Diverse Technology Paths for Generating Motor

Magnetic Fields

Motors convert electrical energy into mechanical energy using magnetic fields. There are multiple ways to create the field: providing the field with permanent magnets, generating it with energized coils, and using differences in magnetic reluctance due to rotor shape to produce torque. The path that avoids rare earths is not limited to one.

Wound-field synchronous motors create a magnetic field by passing current through coils on the rotor side. Induction motors induce current in the rotor through changes in the magnetic field on the stator side. Synchronous reluctance motors utilize differences in the rotor’s magnetic reluctance to obtain torque without permanent magnets or field windings. Even when retaining permanent magnets, there is the option of using ferrite magnets that contain no rare earths.

Material evaluation and motor performance are not directly linked. Maximum energy product is an important indicator for permanent-magnet materials, but its ratio cannot be used to immediately estimate the output, torque, or volume of a single motor. Magnetic circuit design, current loading, degree of reluctance torque utilization, and cooling capability determine the final characteristics. When discussing alternative technologies, it is necessary to distinguish three stages: heavy-rare-earth-free, rare-earth-free, and permanent-magnet-free.

Heavy-rare-earth-free refers to not using heavy rare earths such as dysprosium and terbium. Light rare earths such as neodymium and praseodymium may remain. The heavy-rare-earth-free neodymium magnet announced by Proterial (formerly Hitachi Metals) in 2025 falls into this stage. Rare-earth-free means replacement with magnets containing no rare earths, such as ferrite, but materials called ferrite are not always zero rare earth. Some high-performance ferrites are modified with lanthanum and others, making verification of composition essential. Permanent-magnet-free refers to approaches that change the rotor structure itself, including wound-field, induction, and pure synchronous reluctance types. Each differs in manufacturing process, control, and impact on the supply chain.

Challenges of Already Mass-Produced

Alternative Approaches

Motors that do not use rare earths, or do not use heavy rare earths, are already mounted in mass-produced vehicles. BMW’s fifth-generation electric drive system adopts a wound-field design and does not use rare-earth permanent magnets. According to BMW’s 2021 announcement, motors of this generation had been produced for the iX3 since 2020 and were planned to be expanded to the iX and i4. The keys are stable power supply to the rotating rotor and cooling the rotor itself. The inductive power supply inside the rotor shaft developed by supplier ZF is an effort aimed at brushless power supply, structural simplification, and improved space utilization.

In another direction, there is an approach that combines torque from permanent magnets with torque from reluctance. Ferrite-assisted synchronous reluctance motors, rather than simply replacing magnets, optimize the rotor structure and magnetic path to coordinate the two torques. While practical application of these approaches is advancing, they often involve increased volume, more complex cooling, and performance degradation in specific regions.

What determines the scope of application for alternatives is whether savings in magnet procurement costs are offset by cost increases elsewhere. If additional investment occurs in bearings, reduction gears, cooling systems, and noise and vibration countermeasures, it may not lead to cost reduction for the vehicle as a whole. Material-specific challenges also remain. There are verification items such as the risk of demagnetization of ferrite at low temperatures, brittleness of ceramic-based materials, and ensuring mechanical strength in the high-speed range. Taxi applications do not require extreme instantaneous acceleration, but have high operating frequency. Requirements for continuous efficiency, durability, and maintenance costs are rather stricter, and even with equivalent peak output, operating costs will not necessarily be equivalent.

Do Not Confuse Power Density with Torque Density

The relationship among motor output, torque, and rotational speed is expressed as output P (kW) = torque T (Nm) × speed n (rpm) ÷ 9549.3. At the same output, there is design freedom as to whether to produce large torque at low speed or small torque at high speed. In a typical radial-flux motor, if conditions such as electromagnetic loading are close, torque is roughly proportional to the effective rotor volume. However, if materials, cooling, and structures differ, torque cannot be estimated from overall motor volume alone.

Increasing rotational speed is an effective means to raise power density, but it does not mean an improvement in torque density. In a hypothetical calculation, even if an approach has 70% of the baseline torque at the same volume, if the speed can be doubled, output reaches 140% of the baseline. However, in actual motors, voltage and current constraints, field-weakening control, mechanical strength, and heat dissipation limits hinder higher speeds. Maximum torque and maximum speed are usually at different operating points, and they cannot be multiplied together to be regarded as maximum output. Higher speed itself is not a unique advantage of the ferrite approach and can also be realized with the neodymium-iron-boron approach depending on design. A fair comparison requires aligning the speed range, output requirements, and thermal constraints.

As a specific reference example, there is Proterial’s technical announcement dated July 24, 2023. The announcement used an automotive neodymium-iron-boron permanent-magnet motor as the baseline and built a prototype using ferrite for comparison. Rotor and stator diameters were fixed, with a design considering operating temperature and high-speed strength. However, the brand and model of the baseline motor and the complete test conditions were not disclosed. Calculated from the announced data, the prototype’s output was about 7.3% lower than the baseline, maximum torque 37% lower, and the maximum speed specification 50% higher. This is an example under specific design conditions and does not indicate general superiority of a material path. Results would differ if design targets differed.

The Reality of Refining and Magnet Supply

Held by China

The supply chain structure for rare earths does not change with technology choices for a single motor alone. According to the International Energy Agency (IEA) 2026 report, as of 2024 China accounted for a 91% global share in the refining process for magnet rare earths and 94% in production of sintered rare-earth permanent magnets. A characteristic is the high degree of concentration not only in the mining stage but in mid- and downstream processes such as refining and magnet manufacturing.

Even if a single model switches to no rare-earth use, the demand structure of the industry as a whole will not change immediately. Even if usage per vehicle decreases, if electric vehicle production continues to increase, growth in total demand may only moderate. Vehicles depend on specific supply chains for batteries and electronic components in addition to motors, and if substitution is limited to some materials, it will not lead to diversification of the overall supply chain.

It is premature to see China’s supply chain wavering in the short term. Capabilities in refining and magnet manufacturing, and the accumulation of related equipment, intellectual property, and skills, cannot be transferred overnight. The spread of alternative technologies may have the effect of curbing demand growth, but resolving the existing supply concentration will require multilayered diversified investment including materials, components, and manufacturing equipment, as well as time.

Editorial Opinion

In the short term, the direct impact of Tesla’s announcement on rare-earth markets and competitors’ development plans is seen as limited. Cybercab is a robotaxi for a specific application, and at a stage when mass-production scale and expansion to other models are unclear, it is unlikely to sway the overall picture of magnet demand. Rather, in the next 3 to 6 months, both excessive expectations based solely on company-announced figures and calls for independent verification are expected to rise. Procurement departments are likely to continue a dual response of maintaining alternative sourcing and inventory strategies, while design departments continue prototype evaluation of wound-field and synchronous reluctance types. From a long-term perspective, the significance of rare-earth-free technologies lies in diversification of the supply chain and expansion of design freedom. In 1 to 3 years, approaches such as ferrite-assisted, induction, and wound-field types may progress in segmentation by vehicle size and application. While adoption of alternatives may expand in areas prioritizing cost for small vehicles and areas emphasizing durability and maintainability for commercial vehicles, high-performance neodymium-based magnets are expected to remain in higher-end models requiring high output and high efficiency. From a supply chain perspective, as long as concentration in refining and magnet manufacturing continues, material substitution alone will not resolve structural dependence.

References

• “ 中国稀土的优势地位，就要被这部电机撼动了吗？ “, by 汽车商业评论 — 虎嗅网, 2026-09-18T23:09:36.000Z (ARR)
• Source URL: https://www.huxiu.com/article/4892393.html?f=rss