BYD e⁴ Technology: Redefining Vehicle Control Through Four Independent Motors

As electric vehicles continue to evolve, innovation is no longer limited to batteries and charging speed. The next frontier lies in how vehicles move, respond, and remain stable in extreme conditions. BYD’s YiSiFang Technology, also known internationally as e⁴ Technology, represents a major leap in this direction.

At its core, YiSiFang is a four-motor independent drive control system, with one electric motor assigned to each wheel. Unlike conventional all-wheel-drive systems that rely on mechanical linkages, differentials, and transfer cases, YiSiFang replaces mechanical complexity with precise electronic control. The result is a vehicle that can think, react, and stabilize itself in ways traditional drivetrains simply cannot.

This technology made its production debut on BYD’s luxury off-road brand Yangwang, most notably the Yangwang U8, and it signals a new era of intelligent vehicle motion control.

1. What Is YiSiFang (e⁴) Technology?

YiSiFang literally means “easy four-way,” reflecting its core principle: independent control of all four wheels.

In a YiSiFang vehicle:

• Each wheel has its own dedicated electric motor
• Torque is controlled individually and instantly
• Power distribution is handled entirely by software, not mechanical parts

This architecture allows the vehicle to adjust torque output at each wheel within milliseconds, enabling movements and stability corrections that are impossible for traditional AWD systems.

2. How YiSiFang Differs from Conventional AWD

Traditional AWD systems rely on:

• Central and axle differentials
• Clutches and drive shafts
• Mechanical torque distribution

These systems react after wheel slip occurs and are limited by mechanical response speed.

YiSiFang, by contrast, is:

• Fully electric
• Predictive, not reactive
• Mechanically simplified but electronically sophisticated

Key Comparison

This shift from mechanical logic to digital logic is what makes YiSiFang revolutionary.

3. Performance Capabilities: Power with Precision

YiSiFang is not just about control—it also delivers exceptional performance.

In the Yangwang U8, the system achieves:

• Over 1,000 horsepower (≈880 kW combined output)
• Maximum wheel-side torque exceeding 15,000 N·m
• 0–100 km/h acceleration in approximately 3 seconds (vehicle-class dependent)

But raw numbers tell only part of the story. The real strength of YiSiFang lies in how that power is managed.

Each motor adjusts torque independently, allowing:

• Strong straight-line acceleration
• Precise cornering control
• Continuous traction on uneven surfaces

Even on loose gravel, sand, or wet rock, the system maintains controlled forward motion with minimal wheel slip.

4. Breakthrough Vehicle Dynamics: New Ways to Move

YiSiFang enables several unique driving capabilities that redefine what a vehicle can physically do:

Tank Turn

By rotating wheels on opposite sides in opposite directions, the vehicle can rotate almost on its own axis. This dramatically reduces turning radius—especially useful in tight off-road environments.

Crab Walk

All four wheels steer and drive in a coordinated diagonal direction, allowing lateral movement to escape obstacles or navigate narrow trails.

Emergency Stability Control

If a tire suddenly loses pressure or traction at speed, YiSiFang instantly redistributes torque to the remaining wheels, helping the vehicle remain stable and controllable.

Precision Low-Speed Crawling

For off-road climbing, torque is delivered smoothly and continuously at extremely low speeds—far more precisely than mechanical low-range gearboxes.

These capabilities are not gimmicks; they serve real safety and mobility purposes in demanding conditions.

5. Safety First: Control as a Safety System

YiSiFang significantly enhances vehicle safety by treating motion control as an active safety function.

Key Safety Advantages

• Instant torque correction prevents skidding and loss of control
• Redundancy: even if one motor fails, others continue operating
• Lower rollover risk through dynamic torque balancing
• Improved braking stability via motor-based deceleration

When paired with BYD’s Blade Battery and DiSus intelligent body control system, YiSiFang forms a comprehensive safety ecosystem that addresses both energy and motion risks.

6. Integration with BYD’s Intelligent Systems

YiSiFang does not operate in isolation. It works closely with BYD’s broader technology stack:

• DiSus (云辇): Adjusts suspension height and damping to match torque behavior
• DiPilot / God’s Eye: Uses perception data to anticipate road conditions
• High-speed vehicle domain controllers: Coordinate motor, braking, and chassis response

This integration allows YiSiFang to anticipate scenarios—such as uneven terrain or sudden obstacles—and respond proactively.

7. Why YiSiFang Matters for the Future of EVs

YiSiFang represents a fundamental change in how vehicles are engineered.

Instead of adapting old mechanical concepts to electric power, BYD has redefined motion control from the ground up. This opens new possibilities for:

• Luxury off-road vehicles
• High-performance electric SUVs
• Emergency and rescue vehicles
• Future autonomous platforms requiring extreme stability

As software and sensors continue to improve, the potential of four-motor independent drive systems will only expand.

8. e⁴ vs Global Competitors

While some global brands experiment with dual-motor AWD, very few have brought true four-motor independent drive to mass production.

BYD’s advantage lies in its vertical integration—designing motors, controllers, batteries, and software in-house.

Conclusion: Control Redefined by Electricity

YiSiFang is not simply an advanced drivetrain—it is a new philosophy of vehicle control. By replacing mechanical limitations with software intelligence and electric precision, BYD has created a system that delivers:

• Exceptional performance
• Unmatched control
• Real safety benefits
• New forms of mobility

In the electric era, power alone is no longer enough. Control is the new performance, and YiSiFang places BYD firmly at the forefront of this transformation.

As electric vehicles continue to evolve, technologies like YiSiFang will shape not just how cars drive—but how they protect, adapt, and respond in the real world.