how fast can a self driving car go

[HavenMarie]

The maximum speed of a self-driving car is not determined by its technology's potential, but by a combination of software limits, local traffic laws, and specific operational conditions. In most current deployments, such as those from Waymo or Cruise, these vehicles are geofenced (constrained to specific operational areas) and programmed to obey all posted speed limits, typically cruising at or slightly below the speed of surrounding traffic. On American highways, this means a practical maximum of around 65-75 mph. While some automated test vehicles have reached higher speeds on closed tracks, real-world public use is strictly capped for safety.

The primary constraint is the operational design domain (ODD), which defines the specific conditions under which an automated system is designed to function. A self-driving car’s ODD includes factors like geographic boundaries, road types, speed ranges, and weather. Exceeding these predefined parameters would force the system to issue a fallback request to a human driver or execute a minimal risk maneuver, like pulling over safely.

Speed is also limited by sensor performance. At very high velocities, the sensor suite—including LiDAR, radar, and cameras—must perceive and process information much farther ahead to allow for safe braking distances. Current technology has physical limitations on effective range and data processing speed. Furthermore, regulations in states like California and Arizona, where most testing occurs, require companies to submit safety plans that detail speed limitations.

System / Context	Typical Maximum Speed	Key Factors
Waymo (Urban Phoenix)	45 mph	City speed limits, pedestrian-dense environment
Cruise (San Francisco)	35 mph	Dense urban traffic, frequent stops
Mercedes DRIVE PILOT (Germany)	37 mph	Legal limit for SAE Level 3 conditionally automated driving on approved highways
Tesla Autopilot (Highway, US)	80-90 mph (driver-set limit)	Driver responsibility; system advises against exceeding speed limit
Closed-Course Testing	100+ mph	Controlled environment without public traffic

Ultimately, the goal is not high speed but predictable, safe operation that integrates smoothly with existing traffic flow. The focus for developers is on expanding the ODD to handle more complex scenarios at legally permitted speeds rather than pushing velocity boundaries.

[AmaraLee]

Honestly, it's less about how fast they can go and more about how fast they're allowed to go. My friend works in tech and says the cars themselves are perfectly capable of highway speeds. But the software is programmed to be ultra-cautious. They stick to the speed limit like glue, maybe even a couple miles under. It's all about minimizing risk and proving they're safer than human drivers before anyone even thinks about letting them go faster.

[VivienneFitz]

From a safety engineering perspective, the speed is a function of the system's stopping distance. The vehicle must be able to identify a hazard and come to a complete stop within its sensor range. At 75 mph, that required distance is substantial. Until sensor technology, like next-generation LiDAR, can reliably detect small objects at much greater ranges, high-speed autonomous operation will be intentionally limited. It's a calculated, conservative approach to ensure failsafe operation.

[McMason]

It totally depends on where it's driving. In a busy city, it'll go the speed limit, which is usually 25 or 35 mph. It has to be super careful with pedestrians and bikes. But on an open highway? I'd trust it to do 70 mph, just like a regular car using cruise control. The difference is the self-driving system is constantly watching everything, not getting tired or distracted. The real challenge is handling the transition between those two worlds smoothly.