The 15-inch MacBook Air with the M4 chip represents an iterative but significant update to Apple's popular large-format consumer notebook. Retaining the established thin and light fanless chassis introduced with the M2 generation, the primary evolution is internal, centered around the new M4 System-on-Chip (SoC). This update is strategically timed to align with the industry's shift towards AI-accelerated computing, positioning the Air as a direct competitor to the emerging category of Windows-based Copilot+ PCs. The M4's standout feature is its substantially more powerful Neural Engine, which is projected to deliver over double the tera-operations-per-second (TOPS) of its M3 predecessor. This enhancement is designed to handle on-device AI workloads, from macOS intelligence features to creative and productivity applications, with greater efficiency and speed. While the CPU and GPU also see performance gains, the AI focus signals a clear direction for the product line. ### Key Findings This analysis finds that the M4 Air solidifies its position as a leading premium ultrabook for general users, students, and professionals with mainstream computing needs. Its blend of performance, battery life, and build quality remains a strong proposition. However, its core design philosophy introduces critical trade-offs in sustainability and lifecycle management. The complete lack of user-upgradable RAM or storage, combined with Apple's use of component serialization, results in poor repairability scores and a higher total cost of ownership if upgrades or repairs are needed. This contrasts with its strengths in material circularity, where Apple continues to lead in the use of recycled aluminum, rare earth elements, and other materials. The device exists at a crossroads: it is a highly efficient and powerful machine for its intended lifespan but presents significant challenges for second-life use, independent repair, and long-term hardware adaptability. Strengths: Class-leading performance-per-watt efficiency from the M4 chip and extensive use of recycled materials in the enclosure. Improvements: The soldered, non-upgradable nature of core components like RAM and SSD severely limits repairability and long-term value.