> For the complete documentation index, see [llms.txt](https://www.sdv.guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.sdv.guide/pulse/lean-sourcing/leanrm/why-so-many-requirements.md).

# Why so many Requirements?

The number of requirements for a **new vehicle product line** varies widely based on complexity, regulatory needs, and market positioning. However, here are some general figures:

1. **Traditional Internal Combustion Engine (ICE) Vehicles**
   * **50,000 to 100,000+** requirements
   * Covers mechanical, electrical, regulatory, and safety aspects
2. **Electric Vehicles (EVs)**
   * **100,000 to 200,000+** requirements
   * Includes additional software, battery management, thermal management, and high-voltage safety
3. **Software-Defined Vehicles (SDVs)**
   * **200,000 to 500,000+** requirements
   * Higher complexity due to over-the-air (OTA) updates, software-based functionalities, connectivity, ADAS, and autonomy
4. **Highly Automated / Autonomous Vehicles**
   * **500,000 to 1,000,000+** requirements
   * Integrates AI-driven perception, sensor fusion, redundancy, fail-operational architectures, and extensive regulatory compliance

In modern vehicle development, **40-60% of requirements are software-related**, and this share is increasing with SDVs. OEMs rely on **requirement management tools** (e.g., Polarion, DOORS, Codebeamer) to track and validate these requirements across product lines.

### **Example: Airbags**

The Airbag sub-systems of a car can easily have 50,000-80,000 requirements associated with them. Here is why

### **1. Functional Requirements**

* **Deployment Logic:** When should the airbag deploy? (E.g., frontal impact > 25 km/h)
* **Multi-stage Deployment:** Different force levels depending on crash severity.
* **Passenger Sensing:** Detecting occupants (adult, child, empty seat).
* **Side Airbags & Curtain Airbags:** Coordinated deployment in different crash scenarios.

***

### **2. Safety & Redundancy**

* **Redundant Triggering Circuits:** Prevent false positives/negatives.
* **Fail-Safe Mechanisms:** System must self-diagnose failures.
* **Sensor Fusion:** Integration with accelerometers, gyroscopes, and radar.

***

### **3. Regulatory & Compliance Requirements**

* **FMVSS 208 (USA):** Occupant crash protection standards.
* **UNECE R94/R95 (Europe):** Frontal & lateral impact regulations.
* **China NCAP, Euro NCAP, IIHS:** Different rating system compliance.

***

### **4. Hardware & Material Constraints**

* **Inflator Chemistry:** Must be stable under various temperatures.
* **Fabric Strength:** Must resist wear and environmental degradation.
* **Connector Reliability:** Must withstand vibration and corrosion.

***

### **5. Integration with Other Systems**

* **Seatbelt Pretensioners:** Airbag must coordinate with them.
* **ADAS (Advanced Driver Assistance Systems):** Adjustments based on predicted impact.
* **Vehicle Architecture:** Different requirements for SUVs vs. sedans.

***

### **6. Software & Communication Protocols**

* **CAN Bus Messaging:** Ensure proper timing of deployment signals.
* **OTA Updates:** Requirements for software-based calibration.
* **Self-Diagnostics & Logging:** Error codes, sensor failures, and remote monitoring.

***

### **7. Testing & Validation**

* **Crash Test Scenarios:** Dozens of crash speeds, angles, and occupant sizes.
* **Environmental Testing:** Extreme heat/cold, humidity, aging simulation.
* **End-of-Line Testing:** Every unit must pass factory quality control.

***

#### **Why 80,000+ Requirements?**

Each of these **top-level requirements** branches into **hundreds of sub-requirements**, covering:

* **Component-level details** (e.g., inflator pressure curve specs).
* **Software constraints** (e.g., real-time response deadlines).
* **Testing conditions** (e.g., crash test dummies of different weights).
* **Country-specific compliance differences**.