Cadillac’s new Super Cruise driver-assist feature shows promise as perhaps the most responsible semi-autonomous approach available to consumers today, Consumer Reports has found in its first extended use of the system.

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The system is limited to specific roads, and it goes farther than any previous system in monitoring a driver’s engagement. It also brings more clarity than its competitors to the issue of who’s actually in control of the vehicle, the driver or the computer. And when it's the computer, you're supposed to take your hands off the wheel.

“The way that Cadillac has implemented Super Cruise is the best example we've seen so far of a semi-autonomous feature that offers convenience without trading off on safety,” says Jake Fisher, director of auto testing at Consumer Reports. “Too many of these features give drivers the impression that they can pay less attention to what’s going on. Super Cruise monitors drivers intently to make sure that they’re engaged in a way that no other current system does.”

Several driver-assist features found in many mainstream cars today serve as the building blocks of semi-autonomous driving. Forward-collision warning and automatic emergency braking are proven safety features that reduce crashes, Fisher said.

Other driver-assist tools, such as adaptive cruise control and lane-keeping assist, are more for convenience and they aim at reducing driver stress. They don't necessarily make drivers any safer, Fisher says, and they are clearly not ready to handle every driving situation.

Our findings are preliminary, but our testers have already driven hundreds of miles using Super Cruise in our 2018 Cadillac CT6.  We will continue using and evaluating it, and will report on our findings as we learn more.

2018 Cadillac CT6 with Super Cruise
Red signals for the driver to take control.

Why Super Cruise Is Different

There are four key aspects that CR testers like about the Super Cruise approach:

  • It works only on specific highways, those with at least four lanes of traffic, that have limited access, and have no cross traffic. That’s the safest environment for semi-autonomous driving, Consumer Reports believes, because it's much easier for the system to deal with this more predictable environment. GM has mapped more than 160,000 miles of these highways across the U.S. and Canada in preparation for Super Cruise.
  • It does a better job of monitoring driver engagement. Instead of using pressure on the steering wheel as the indicator of driver involvement, as many other systems do, the Super Cruise system uses sensors to track where the driver’s eyes are looking (more details are below).
  • The system gives drivers advanced warnings when it’s going to hand over control to the driver. The system constantly has data about the next 2,500 meters in front of the car (about 1.5 miles), so it knows about curves, exit-only lanes, and the like before the driver gets there. It uses that information to clearly alert drivers of upcoming changing conditions, and their need to retake control of the vehicle.
  • It reduces the ambiguity about who’s in control of the car, the driver or the computer, by using a bright light bar on the steering wheel. When it’s blue, the driver is in charge, green means the computer is driving, and red means the driver needs to immediately take back control of the wheel. In too many systems CR has driven, drivers feel like they’re “fighting” the car for control of the steering, particularly with lane-keeping systems. In the Super Cruise, when a driver wants to change lanes, as soon as the driver grasps the wheel and turns it, the light changes from green to blue, and the driver has control and can change lanes. Once the system identifies that it’s in the center of the new lane, the light changes back to green, and the computer takes over.
2018 Cadillac CT6 with Super Cruise
Blue reinforces that the driver has control of the car.

It may seem counterintuitive that keeping your hands off the wheel could be safer, but in this case, it helps to reduce ambiguity over control, Fisher says.

“The hand-off from car to driver is more clear, more seamless, and happens earlier,” he notes.

Drivers will want to keep their hands off of the wheel, because if they don't, they could inadvertently turn Super Cruise off. The system understands that when the driver puts pressure on the steering wheel, the driver's intent is to change lanes, or take control. A driver resting his hands on the wheel while Super Cruise is engaged will only confuse the system.   

The system isn’t perfect. Among the issues testers encountered:

  • Occasionally Super Cruise displays a notification that it’s not available even though conditions appear to be right for it. GM acknowledges that this can happen, and says it’s constantly revisiting roads in an effort to keep them current. This should improve over time, GM says.
  • Going around curves can feel a little strained at times, and the car is often pulled to the edge of the lane, which can be disconcerting.
  • One tester said the eye-tracking system had a hard time knowing if he was watching the road because the morning sun was reflecting off of his sunglasses, and frequently reminded him to pay attention, even though he already was doing so.
2018 Cadillac CT6 with Super Cruise

How Does Super Cruise Work?

Like other driver-assist systems, Super Cruise uses cameras and radar to “see” lane lines and help keep the car centered, and appropriately behind other vehicles.

In addition to those technologies, though, it also employs global positioning satellite and lidar (light detection and ranging, a technology that’s basically a more advanced, laser-based version of radar) mapping technologies to understand where the car is and what the area around it is like.

This is part of what’s different about Super Cruise from most other driver-assist systems: It “knows” if the vehicle is on a divided, limited-access highway, and only then allows drivers to engage the system. Other driver-assist systems have an awareness of what type of road the car is on, but they aren't as restrictive with where they allow operation as the Super Cruise is.

On top of that, the system also keeps a literal eye (camera) on the driver’s head and eyes, which is supported by infrared sensors. So beyond knowing where the car is, and whether it’s on an appropriate roadway, it also knows if the driver is looking at the road. If it senses that the driver is not paying attention to the road, it will alert the driver, and will ultimately disable the system if the driver does not show signs of engagement in time.

That disabling is not a complete, sudden shutdown of the system, though. In a multistep process, the driver gets warning lights on the steering wheel, audible alerts, and/or a vibrating seat before the system starts to slow the car down.

If there is still no response after all of that (say the driver became incapacitated for some reason), then the car’s brakes are applied while the car is kept on its current path until it stops. Just before it stops, the hazard lights are automatically turned on, and a call is placed to OnStar operators; OnStar is GM’s in-car telematics system.

Read our complete Cadillac CT6 road test.