Consumer Reports ranked the brand’s SuperCruise system first of the four driver assistance systems it evaluated, including Tesla’s Autopilot, Nissan’s ProPilot Assist and Volvo’s Pilot Assist. It is the same choice Business Insider made earlier this year in an independent test.

No commercial car available today is a full self-driving system, according to the U.S. National Highway Transportation Safety Administration’s six-level classification system. Instead, the systems offer drivers a respite from the more repetitive tasks of driving, such as staying in the line on long stretches of highways or handling stop-and-go traffic.

Cadillac’s system was the only one that scored full points in any category that Consumer Reports evaluated. It earned them in the ‘Clear When Safe to Use’ category. One of the psychological risks of taking the wheel from drivers is that drivers may not necessarily be ready to take it back when necessary. So carmakers must be careful about the circumstances in which a car can offer assistance to drivers in the first place.

Tesla (TSLA) earned the lowest possible score in the ‘Keeping Driver Engaged’ category and outscored Cadillac in the ‘Capability & Performance’ category.

“The best systems balance capability with safeguards—making driving easier and less stressful in the right situations. Without proper safeguards, overreliance on the system is too easy, which puts drivers at risk,” said Jake Fisher, director of auto testing at Consumer Reports.

The Cadillac system trains a camera on driver’s faces and uses machine vision to determine if the driver is getting distracted or sleepy. It also only operates on divided highways without intersections where GM (GM) has made its own maps.

The less driver assistance systems trust drivers, the better. A recent study found that humans were responsible for most accidents involving self-driving cars.