Modern cars rely on software across many electronic control units (ECUs), from powertrain and body systems to infotainment, connectivity and driver assistance. UNECE reported in 2020 that cars could contain up to 150 ECUs and about 100 million lines of code, and projected that figure to reach 300 million lines by 2030. Software helps vehicles coordinate complex functions, but it also makes updates, cybersecurity and data handling important parts of vehicle ownership.
How much software is in a car?
There is no single software count that applies to every car: the amount varies with the vehicle, its equipment and how its systems are organized. UNECE’s 2020 description put the scale at up to 150 ECUs and about 100 million lines of code in cars at that time. UNECE projected that code total would rise to 300 million lines by 2030; that is a projection, not a verified count for every vehicle or a confirmed present-day total.
An ECU is an electronic controller that runs software for one or more vehicle functions. A car’s software is not necessarily one program in one computer: it can be distributed among controllers and connected systems, alongside software in manufacturer infrastructure and companion apps.
What does car software control?
The functions vary by vehicle. Some software operates systems that affect how the vehicle moves or responds; other software supports comfort, information, communication or maintenance.
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| Software area | What it is used for |
|---|---|
| Powertrain and vehicle systems | Control functions associated with the powertrain and other vehicle systems. |
| Body systems | Manage body-related functions through vehicle controllers. |
| Driver assistance and automated driving | Support assistance or automated-driving functions, where fitted. |
| Infotainment and connectivity | Provide in-car information and connected features. |
| Diagnostics | Help identify faults and support vehicle servicing. |
These categories describe different roles, not a guarantee that every car has every feature. Software also exists beyond the vehicle itself: cloud services, mobile apps and update-management systems can support connected functions without being the same thing as ECU firmware installed in the car.
How do car software updates work?
An over-the-air (OTA) update is a software package delivered remotely to a vehicle. Not every update is OTA; software may also be installed through other manufacturer-controlled service or delivery processes. Under UNECE Regulation No. 156 (R156), software-update management is a controlled engineering process, rather than simply sending a file to a car.
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- Identify the target vehicles and software. The manufacturer records software versions and identifies which vehicles and systems are intended to receive the update.
- Check compatibility and approval impact. The update must be assessed for compatibility and for whether it affects safety or parameters covered by legal approval or type approval.
- Protect the package. Delivery integrity and authenticity must be protected so the vehicle can verify that the software is the intended update and has not been altered.
- Prepare safe installation conditions. The process must provide sufficient power and ensure that the update can execute safely.
- Plan for failure and recovery. The manufacturer must account for update failures and provide a recovery approach rather than leaving an unsuccessful installation unmanaged.
- Inform the owner and document the work. User information, records and documentation are part of the update process.
ISO 24089:2023 sets out engineering requirements and recommendations for software updates. Its scope includes vehicles, vehicle systems, ECUs, update infrastructure, and the assembly and deployment of update packages, including work by manufacturers, suppliers, subsidiaries and partners. R156 is a UN regulation; whether and when its requirements apply to a vehicle depends on the relevant jurisdiction and its implementation.
Can an update make a car safer or add features?
Software can affect vehicle behavior, so an update may be used to address software issues or change a function. Whether an update improves safety, adds a feature or changes a legally approved parameter depends on the specific update and vehicle. R156’s safety and type-approval assessment requirements are one reason those effects cannot be assumed from the fact that an update is available.
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Before installing an update, follow the vehicle manufacturer’s instructions and review any owner information it provides. The update process should account for safe execution conditions and failure recovery; owners should not treat an interrupted or failed update as an ordinary app-installation problem.
Why are cybersecurity and privacy part of the software story?
Connected and automated vehicles can have interfaces to external networks, backend servers, mobile apps, sensors and in-vehicle communications. Each connection or interface can contribute to the vehicle’s attack surface. A cybersecurity problem can therefore be relevant to vehicle safety as well as data protection.
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UNECE’s cybersecurity framework calls for manufacturers to manage risk through secure design, assessment and mitigation, monitoring, incident detection and response, and evidence that mitigations work. NHTSA’s 2022 best-practices update is non-binding U.S. guidance, informed by agency research, industry standards and public comments. NHTSA described cybersecurity as critical to the safe future deployment of connected and automated vehicle technologies.
Privacy is another consideration for connected systems, but what data a particular vehicle collects, how it is used and how long it is retained cannot be determined from the general fact that a car has software. Those details need to be checked in the relevant vehicle’s settings, documentation and privacy disclosures.
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What should you compare when evaluating a car’s software?
Software capability is more than a feature list. For a useful comparison, check the following points for the specific vehicle, trim and market:
- Function: Which infotainment, powertrain, assistance, connectivity and diagnostic features are actually included?
- Safety criticality: Which functions can affect vehicle operation, and how does the manufacturer describe their limitations?
- Update path: Are updates delivered OTA, through a dealer or service visit, or by another method?
- Cybersecurity governance: What update and cybersecurity management processes does the manufacturer describe?
- Data and privacy: What connected data is collected, and what controls or disclosures are available?
- Interoperability: Which connected services, apps or other systems does the software work with?
- Support period: How long does the manufacturer say software and connected services will be supported?
- Jurisdiction: Which rules apply where the vehicle is sold or used? UNECE regulation implementation dates vary by jurisdiction.
For technical discussions, distinguish vehicle-level software from ECU firmware, cloud services, mobile apps and the systems that manage updates. They interact, but they are not interchangeable terms, and a claim about one layer does not establish how another is secured or supported.
Why are manufacturers investing in automotive cybersecurity?
UNECE cited automotive cybersecurity investment of USD 4.9 billion in 2020 and USD 9.7 billion in 2030. The latter is a 2030 projection cited by UNECE, not a confirmed spending total. The figures indicate the scale of investment UNECE anticipated as vehicle connectivity and software-related risks grew.
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