Washington, DC (CNN Business) Tesla has said its latest version of Autopilot, its autonomous driving software, is able to stop at traffic lights. But some Tesla drivers are learning it doesn't just stop at red lights, it appears to slow down for green lights, too.

Last Friday, Tesla drivers first reported receiving a software update that included "Traffic Light and Stop Sign Control," which is designed to slowdown and stop the vehicle for visible traffic lights or stop signs.

Tesla TSLA describes the software as being in "beta," meaning it's unfinished and still officially in testing. It's designed to gradually improve as the artificial intelligence that powers it learns from the data that's being collected as Tesla cars drive on public roads, according to a notification in Tesla vehicles when the system is first activated.

A visual prompt appears on the dashboard as the car approaches an intersection that reads, "Stopping for traffic control in 300 ft. Use accelerator or cruise stalk to continue." The number of feet in the message appears to change depending on how close the vehicle is to the stop sign or traffic signal.

"This feature will be conservative, slowdown often at first, and will not attempt to turn through intersections," Tesla says in a statement shown in the console screen of Tesla owners' vehicles after the update is installed.

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