The automotive industry is charting a new course in steering technology with the advent of true steer-by-wire systems, which eliminate the traditional mechanical link between the steering wheel and the front wheels. This innovation promises features such as infinitely variable steering ratios and the isolation of unwanted feedback from road imperfections. While early implementations, like the 2014 Infiniti Q50, retained a mechanical fail-safe—a clutch to reconnect a physical shaft in case of system failure—the latest generation of these systems, exemplified by the Tesla Cybertruck (2025 Best Tech–winning) in North America and the Nio ET9 in China, have entirely removed this reconnectable shaft.

Mercedes-Benz is set to join this exclusive group, becoming the first German automaker to offer true by-wire steering with the launch of its 2027 Mercedes-Benz EQS-Class sedan. Having experienced all three systems—Tesla, Nio, and the forthcoming Mercedes-Benz—a clear comparison highlights their approaches to safety and functionality in a post-steering-column future.

A critical aspect of these advanced steering systems is abundant redundancy, ensuring operational integrity even in the event of component failure. All three manufacturers—Mercedes-Benz, Tesla, and Nio—implement at least two of every essential component. This includes two separate DC-DC converters and power supplies, two completely disparate communications circuits, and steering motors equipped with two separate stator windings. If a failure is detected in one circuit, the other immediately takes over, maintaining steering control.

Nio and Mercedes-Benz go a step further in their redundancy measures, utilizing materially different CPUs, software, and in some cases, hardware to prevent a common failure path from crippling both circuits simultaneously. Both companies also incorporate a third set of steering angle sensors. These sensors are on standby to determine which of the two primary sensors is correct should their signals ever diverge, a protocol borrowed from aerospace safety standards. Furthermore, both Nio and Mercedes-Benz systems have received safety certifications from their respective national governing bodies, underscoring their commitment to reliability. Tesla, however, has provided less transparency regarding the specific functionality and certification of its system.

The fail-safe protocols for these steer-by-wire systems are meticulously designed to ensure driver safety under various error conditions. In the Mercedes-Benz system, if an error is detected in either of the main steering circuits, the vehicle automatically enters a 'limp-in' mode. This mode restricts the car's speed to 54 mph and limits the driving distance to allow the EQS to safely exit even the world's longest highway tunnel, the 15.2-mile Laerdal in Norway. In the infinitesimally small likelihood that both primary systems were to fail simultaneously, the Mercedes-Benz EQS is engineered to utilize its rear-wheel steering and selective braking to guide the vehicle along the driver’s intended path. Nio employs a similar strategy, forcing the car to a safe stopping point sooner rather than later. Tesla’s approach, upon fault detection, involves flashing numerous warnings to the driver but allows continued use of the backup system, albeit with reduced functionality, and without a self-parking end-game in the event of total system failure.