Consumer Reports: Tesla Autopilot illegally 'cuts off cars'

The report claims the driver assistance technology still requires frequent intervention.

Consumer Reports has issued another criticism of Tesla's Autopilot technology, claiming the latest update "doesn't work very well" and poses a potential safety risk for drivers.

The magazine takes issue with how the system automatically changes lanes, without first receiving driver permission. The author claims the feature "cut off cars without leaving enough space and even passed other cars in ways that violate state laws."

To be fair, Tesla and other companies developing autonomous technology face a difficult conundrum in deploying technology that can effectively maneuver in environments where human drivers are technically breaking the law. In a congested environment such as Los Angeles rush hour, merging onto a highway is sometimes impossible without turning into a small slot.

"The system has trouble responding to vehicles that approach quickly from behind," said CR auto testing director Jake Fisher. "Because of this, the system will often cut off a vehicle that is going a much faster speed since it doesn't seem to sense the oncoming car until it's relatively close."

Fisher also claims Autopilot is reluctant to merge into heavy traffic, and when it does, it often "immediately applies the brakes to create space behind the follow car."

Human drivers typically coast after merging into heavy traffic to increase following distance. This leaves the merging vehicle in violation of "following too closely" laws for a longer period of time, however.

"Monitoring the system is much harder than just changing lanes yourself," Fisher argued. "Using the system is like monitoring a kid behind the wheel for the very first time. As any parent knows, it's far more convenient and less stressful to simply drive yourself."

Tesla has promised to roll out an even more aggressive merging option, allowing drivers to accept a "nonzero chance of a fender bender" in freeway traffic, according to Elon Musk's recent Autopilot event. The company aims to launch Full Self-Driving -- with driver monitoring, at first -- sometime next year.