Even if a Waymo vehicle drives through a city with no one in the driver’s seat, its autonomous driving rating is still Level 4, not the top Level 5.

Engadget reported on Aug. 22 that the final stage of self-driving is determined less by whether a human intervenes and more by whether the system can operate without limits in any environment.

From the outside, Waymo may appear to have reached full autonomy. For riders, there is no steering input, no need to monitor driving, and no reason for a person to intervene. The vehicle handles the entire process of travel on its own.

But the Society of Automotive Engineers (SAE) standards for autonomous driving put more weight on the scope in which that independence is allowed than on how independent it appears. The key difference is not how independent it looks in real driving, but where that independence is permitted.

Level 4 is the stage in which the system can perform the entire driving task without human input, as long as it stays within defined conditions and areas. Even if a Waymo vehicle moves without a driver in urban traffic, it is classified as Level 4 if that capability is guaranteed only within specific areas and conditions. In other words, Level 4 applies when fully autonomous driving is possible within defined conditions and locations.

Level 5, by contrast, removes those limits. The system must handle every driving situation on its own without boundaries such as a specific city, road type, weather or operating area. To reach Level 5, those boundaries must be eliminated entirely.

This distinction is also a yardstick for competition in self-driving technology. That is because it is difficult to judge whether a system is at the highest level based only on the driverless experience felt by ordinary users. In actual classification, it matters more whether a vehicle can perform at the same level of driving reliably anywhere than whether it appears to drive without a person.

Against that backdrop, Waymo’s current position is described not as the end point of technical completion but as an advanced autonomous driving stage with a limited operating range. Even if the vehicle handles the entire trip by itself, it remains at Level 4 if applicable places and conditions are limited. Because Level 5 requires the absence of any regional or conditional constraints, the gap between the two levels is large.

Ultimately, the highest stage of autonomous driving is not decided just by the sight of an empty driver’s seat. If fully autonomous driving is possible only within defined areas even without a person, it is Level 4. To be recognized as Level 5, the same level of autonomous driving must be possible in all environments without any boundaries.