Why don't cars use Ethernet?

1, History and technological inertia
Firstly, the technological development of the automotive industry has a profound historical accumulation and technological inertia. Early automotive control systems were mainly based on analog circuits and simple digital circuits. With the introduction of electronic control units (ECUs), specialized automotive network protocols such as Controller Area Network (CAN) and FlexRay gradually became industry standards. These protocols were designed with consideration for the unique characteristics of the automotive environment, such as electromagnetic interference, high temperatures, vibrations, etc. After years of practice and optimization, they have formed a mature and stable ecosystem. Therefore, although Ethernet has advantages in data transmission speed and flexibility, it is not easy to replace these deeply rooted protocols in a short period of time.
2, Cost and complexity considerations
Cost is one of the key factors limiting the widespread application of Ethernet in automobiles. Compared to traditional automotive networks such as CAN bus, Ethernet requires more complex hardware support, including high-performance switches, routers, and physical layer interfaces that support gigabit or even higher bandwidth. This not only increases the cost of individual components, but also puts higher demands on the wiring, connectors, and power management of the entire vehicle. In addition, in order to achieve effective deployment of Ethernet inside automobiles, specialized network management software and protocol stacks need to be developed, which increases the complexity and development costs of the system.
3, Real time and reliability requirements
A core requirement for the internal network of a car is real-time, which means that data must be transmitted from the source to the destination in a very short amount of time to ensure the safe operation of the vehicle and the comfort of passengers. Existing protocols such as CAN bus can achieve high reliability communication with low latency through simplified protocol stacks and optimized transmission mechanisms. However, Ethernet, especially in an unoptimized state, may experience increased latency due to network congestion, packet retransmission, and other factors, which is unacceptable for automotive control systems that require rapid response. Although real-time performance can be improved through technologies such as priority division and Time Triggered Ethernet (TTEthernet), these require additional design and implementation costs.
4, Standardization and compatibility challenges
The standardization process in the automotive industry is relatively slow, and the technical barriers and conflicts of interest between different manufacturers make it difficult to quickly promote a unified Ethernet standard. In addition, there are a large number of legacy systems in the existing automotive network, and ensuring compatibility between newly introduced Ethernet devices and these systems is also a major challenge. Although organizations such as OPEN Alliance are actively promoting standardization of automotive Ethernet, achieving this goal comprehensively will still take time.
5, Security and Privacy Issues
With the development of intelligent and networked automobiles, network security and privacy protection have become issues that cannot be ignored. Ethernet, as an open network technology, is more susceptible to the risks of hacker attacks and data breaches. Although security measures such as encryption and firewalls can enhance protection, this undoubtedly increases the complexity and cost of the system.