I had two callers to my radio show Saturday tell me, politely, that I am wrong about Tesla’s Full Self-Driving system. Both use FSD regularly, both say it works extremely well, and both clearly have tremendous confidence in it. I listened to them, and I believe them. I learned from them and I am grateful for the information. That does not mean I have completely changed my mind. I have probably been too dismissive at times about just how good Tesla’s latest Full Self-Driving technology has become. There are owners using it for thousands of miles who report very few interventions, and recent independent road tests have found enormous improvement over earlier versions that I tested. But there is a distinction I think every driver needs to understand: a system can be remarkably capable and still not be autonomous. Even Tesla makes that distinction. The product is now formally called Full Self-Driving (Supervised), and Tesla states plainly that it requires an attentive driver, does not make the vehicle autonomous, and requires the driver to remain ready to take control at any moment. Tesla classifies FSD as a Level 2 driver-assistance system. That “Level 2” designation is important. Under the automation definitions used by NHTSA and SAE International, Level 2 means the vehicle can control steering and acceleration/braking at the same time, but you are still driving. You are responsible for watching the road, obeying traffic laws and intervening whenever necessary. Take your hands off the wheel if the system permits it, but you cannot take your brain out of the driver's seat. Tesla FSD is unusually ambitious for a Level 2 system. It can operate on city streets as well as highways, follow a navigation route, change lanes, negotiate intersections and roundabouts, make turns and park. Tesla says its vehicles