In a blog post on Thursday, Tesla announced that drivers will no longer have to approve lane changes when the car's Navigate on Autopilot system is engaged.

It's a small step, but also a pretty big leap toward self-driving cars.

Navigate on Autopilot is Tesla's "on-ramp to off-ramp" self-driving system, which allows its cars that have the feature to drive themselves on limited access highways and navigate interchanges, on-ramps, and off-ramps by themselvesas long as the driver keeps a hand on the wheel periodically and the car has a destination set in the navigation system. 

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On surface streets leading toward or away from limited access highways, the Navigate on Autopilot system shuts off.

Until now, though, the cars couldn't change lanes without driver approval. When they encountered slower traffic, or even need to change lanes to take an off-ramp, the car would alert the driver of the need to change lanes, and the driver would have to approve the lane change by activating the turn signal.

Without the need for that intervention the car is much more autonomous in getting from place to place. It still chimes at drivers before the car changes lanes to give the driver a chance to ensure that it's safe to do so. 

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Drivers can still set the car to require turn signal interventions, and Tesla says, "until truly driverless cars are validated and approved by regulators, drivers are responsible for and must remain in control of their car at all times."

The new software update will also allow driver to set Navigate on Autopilot to turn on automatically every time they start the car, as long as a destination is entered.

Since Tesla rolls out its new software features gradually, to a few owners' cars at a time, it has already been pilot testing the turn-signal-less feature for several months. The company says drivers in its Early Access Program, as well as Tesla engineers testing, have already driven half a million miles with Navigate on Autopilot.

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When the company announced the introduction of the base-priced $35,000 Model 3 at the end of February, Tesla CEO Elon Musk said company's Full Self-Driving Capability will be "feature complete" by the end of this year.

Such systems, while they may work perfectly most of the time in situations they were designed for, might be prone to sudden (and sometimes tragic) failure if they encounter something beyond their capabilities.

Tesla has been careful to emphasize in its recent communications that drivers still have to stay alert and engaged while using the system.