Last month, on the National Highway Traffic Safety Administration’s investigation into Autopilot-related Tesla collisions with emergency vehicles. Now, it seems Tesla has quietly updated their Level 2 driver assist software to detect and react to emergency vehicle lights.

Tesla recently began pushing out to vehicles, and owners of the Model 3 and Model Y quickly noticed a change that wasn’t in the release notes. An interesting tidbit popped up in their in-car owners manuals, per Twitter user :

It seems that, in limited cases, Tesla vehicles will now slow down while passing stopped emergency vehicles on the highway. This feature has yet to be confirmed in any patch notes (read: Elon Musk’s Twitter account) but has been for Autopilot.

While slowing down for emergency vehicles is better than not doing so (and in some cases, ) the timing of the update seems to coincide with the investigation.

The update specifies that Teslas will only identify emergency vehicle lights at night, and not in all cases. While most crashes under NHTSA investigation , the limitations on the software pose interesting questions for Autopilot’s ability to differentiate real police cars, fire trucks, or ambulances from other visual white noise.

Can the camera system in a Model 3 distinguish flashing red and blues against a bright midday sky, when the lights won’t have the same chiaroscuro to make them pop? Alternatively, is the restriction meant to limit false positives from sunny reflections on colored surfaces? Until Tesla publishes a patch note, we won’t know for sure.

Without clear information about the capabilities and limitations of this new feature, it’s unclear exactly how it will work in the real world. We don’t yet know how much a Tesla will slow down as it passes parked emergency vehicles. In fact, the text of the owner’s manual doesn’t even specify that emergency lights must be stationary — it’s possible a Model Y or Model 3 using Autopilot may slow down when being passed by an emergency vehicle.

Time will tell how this update functions in practical applications, and if it will have any effect on the ongoing investigations into Tesla.