Not all self-driving technologies are as self-driving as others. The Society of Automotive Engineers (SAE) and the US National Highway Traffic Safety Administration (US NHTSA) have both issued guidelines for what the various level of autonomy mean in cars.

Level 0 means humans do everything in both systems. Here are the 5 other levels of autonomous driving. To keep things clear we’ll give you the SAE levels and then explain where the US NHTSA fits in.

SEE: Our autonomous future: How driverless cars will be the first robots we learn to trust

Level 1

For the SAE this means Parking assistance, lane keeping and systems where the driver has to be ready to take control at a moment’s notice. The US NHTSA calls that Level 2. The NHTSA’s level one is individual systems like automatic braking.

SEE: Video: See how 2017 Ford Fusion Energi will be equipped with semi-autonomous features

Level 2

For the SAE this is the car driving most of the time with the driver intervening for events or unexpected objects. The system deactivates as soon as the driver takes over.

Level 3

Both the SAE and NHTSA say at level 3 the driver can cede all safety-critical functions to the car under certain conditions. The SAE defines level 3 as operating in known limited environments like freeways. Otherwise the driver has to pay attention.

Level 4

The SAE calls level 4 the one where the car can do the driving in all but a few environments like severe weather. That’s covered in level 3 by the NHTSA.

Level 5

No human driver is required. The car doesn’t even need steering wheels or brake pedals, as the machine does all the driving. The NHTSA calls this level 4.

SEE: Level 5 autonomous driving comes to all new Teslas

Now when somebody says autonomous car you can ask what level. And then whether they mean SAE or NHTSA. But hey, you’ll at least get a little clarity.

Also see:
Autonomous driving levels 0 to 5: Understanding the differences
US DOT unveils ‘world’s first autonomous vehicle policy,’ ushering in age of driverless cars
Panasonic takes major step toward autonomous driving with its first connected vehicle platform in the US
BMW’s vision for the smart city of the future includes autonomous driving and AI
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