2018 Cadillac CT6 Review: A True Autonomous Car Hits the Highway

Thanks to Super Cruise technology, the self-driving Cadillac CT6 boasts the most accurate system yet for taking your hands off the wheel.

Editor's Choice

Tom's Guide Verdict

Thanks to Super Cruise technology, the self-driving Cadillac CT6 boasts the most accurate system yet for taking your hands off the wheel.


  • +

    Most advanced autonomous driving features yet

  • +

    Impressive video rear-view mirror

  • +

    Teen driver mode

  • +

    Responsive handling with rear-wheel steering

  • +

    34-speaker Bose audio system

  • +

    Supports Android Auto and Apple CarPlay


  • -

    Super Cruise is for highways only

  • -

    Cannot change lanes by itself

Why you can trust Tom's Guide Our writers and editors spend hours analyzing and reviewing products, services, and apps to help find what's best for you. Find out more about how we test, analyze, and rate.

The first car to drive itself — albeit with significant restrictions — has arrived. And it's not from a tech company like Alphabet's Waymo or an upstart like Tesla. It's a Cadillac.

Meet the 2018 Cadillac CT6, the first car with Super Cruise. Unlike all other advanced driver-assistance technologies, Super Cruise is designed to actually drive the car by itself on certain highways.

You do not have to keep your hands on the wheel (or keep touching the wheel) as you have to do with systems from Tesla and Mercedes-Benz, for example. And a test drive proved that Super Cruise is steadier and more accurate than any so-called autopilot system yet introduced, making it a long-distance driver's dream and a commuter's fantasy.

While GM plans to roll the option out in other models, so far, Super Cruise is available only in Cadillac's luxury sedan. The feature is standard on the Platinum version of the CT6 (MSRP: $85,290) and is a $5,000 option on the Premium Luxury model, which starts at $66,290.

Where Super Cruise Works

There are two significant limitations to Super Cruise. The first is that it onlyworks on about 130,000 miles of specially mapped highways in the U.S. and Canada. For safety's sake, the roads, which must be mapped using LiDAR-equipped vehicles, have to be divided highways with no cross traffic (meaning no intersections). Cadillac says the company will continue to add more mapped highways, extending Super Cruise's range.

The second limitation is that the driver has to maintain situational awareness. You cannot watch a movie on your tablet or take a nap. That's because the car is watching you, making sure you remain attentive, lest something should occur that the car cannot handle on its own, such as a sudden detour. In other words, you have to be ready to retake control of the car. (For the technically minded, this makes the CT6 a Level 2 vehicle.)

Self-Driving Done (Mostly) Right

The job of testing and reviewing cars is about to undergo a radical change.

Yes, the Cadillac CT6 is a seductive four-door with lots of giddyup, confident handling and plenty of (orchestrated) guttural notes when you step on the gas. And yes, the appointments within — including a built-in seat massager, a four-zone HVAC system, and a CarPlay- and Android Auto-compatible infotainment system — put it right up there with the best luxury vehicles from Mercedes and BMW.

But the real draw now is that this car will drive itself. And that means that in addition to swinging the Cadillac CT6 through cloverleafs, testers have to lean back and critique how the car handles the road all by itself.

To engage the Super Cruise autonomous mode, you first have to turn on adaptive cruise control. Once that's successfully engaged, if the highway happens to be one in the Super Cruise system, a white steering wheel icon will appear in the driver's LCD instrument display.

Most semi-autonomous 'pilot' systems hunt for the lines on the road and sometimes ping-pong back and forth. The CT6's Super Cruise never did that.

Center the car in your lane, hit the Super Cruise button next to the adaptive cruise control button, and when the LED light bar on the top of the steering goes green, you can hand over control to the car. (You still have to change radio stations on your own.) I found engaging the system simple enough, and after a bit of practice, I was able to turn it on and off with ease.

On I-95 and other highways in New Jersey, the CT6 drove with a steady hand. Most semi-autonomous "pilot" systems tend to hunt for the lines on the road and sometimes ping-pong back and forth within the lane. The CT6's Super Cruise never did that, remaining dead center in the lane, even on broken pavement that was under construction. After a few minutes watching how well the car behaved, I relaxed as the CT6 ably passed between tractor trailers going 65 mph. The only deviations I detected were the occasional milliseconds of hesitation as the car sped past an exit ramp (that's where the camera would see the right-hand white lines diverge).

Room for Improvement

For all its impressive skills, Super Cruise cannot perform complex maneuvers like changing lanes to pass a slower vehicle. To do that, you have to take the wheel, signal and make the maneuver yourself, during which time, the steering wheel light will turn blue. Once you're back in your lane and have carefully centered the car, the green light comes on again and you can let go; there's no need to reset the speed, etc.

Countless other situations will crop up, however, that demand human attention. For example, while on one stretch of highway, I noticed a black sedan on an entry ramp that was shortly going to want to merge into my lane of travel. However, Super Cruise does not recognize such situations, so the CT6 continued on at the same speed. Eventually, the merging vehicle had to brake to enter the highway behind me. Normally, I would have slowed slightly to let the other vehicle in.

For these reasons, Super Cruise has to include the driver attention detection system. Misbehave or block the camera, as I did, and the car goes through various warning levels — there are audible chimes and the steering light flashes and then turns red — before finally bringing the vehicle to a halt within the lane of travel (it will not pull off the road). I didn't fully test the car’s patience and was able to reset the system after a brief warning. However, should one abuse Super Cruise, the car not only stops but also disables the self-driving feature. The CT6 then has to be turned off and then on again to allow the use of Super Cruise.

MORE: Connected Cars: A Guide to New Vehicle Technology

There are still some things that need to be updated and adjusted in the Super Cruise software. For example, the system does not indicate why it has given you a flashing red-light warning. Sometimes, the reason is that the car is no longer fully cognizant of its location, likely due to roadwork or inclement weather. Other times, it's because you looked away from the road for too long. In other cases, it's because you momentarily blocked the camera's view. The Cadillac's dashboard should tell you why you've received a warning, so that you can learn how to properly work with the system, and hopefully become more attentive rather than more distracted.

Misbehave or block the camera, as I did, and the car goes through various warning levels before finally bringing the vehicle to a halt within the lane of travel.

Furthermore, you cannot currently use the nav system to find Super Cruise compatible highways and plan your trip to favor such roads. However, a Cadillac spokesperson said the company is planning to put all currently mapped highways online, as well as add the navigation feature to Cadillac app.

The Tech

The CT6 comes with forward-facing radar and a video camera. Additional side-mounted cameras cover the blind spots, and a camera system in the back delivers a unique, wide-angle picture of what's behind you at all times. That last feature all but eliminates blind spots in back, because it isn't limited by a small rear window, blocked by passengers sitting in back or obstructed by the rear roof pillars. The resulting image is displayed in the rearview mirror, replacing the usual mirror image.

Unlike most autonomous test vehicles, there is no LiDAR (light detection and ranging) system in the CT6. LiDAR is generally used to give self-driving cars a detailed 3D view of the road and their surroundings, including curbs, lampposts and any elevation changes. Instead, GM uses downloaded maps of highways that have already been created for the company using LiDAR. Together with the built-in GPS and the radar and video information, the Cadillac thus has a precise reading of where you are and what's ahead. There's still a limit to how far the car can "see" ahead (about 2,500 meters, according to GM), so Super Cruise will not work above  85 mph.

The other critical component of Super Cruise is the driver attention detection system. Using infrared sensors in the steering wheel and a video camera mounted on the top of the steering column, this system tracks eye movements, as well as the driver's face and head position. It works day or night, and whether or not you're wearing sunglasses. Even though the car will drive itself for an unlimited amount of time on approved highways, Super Cruise is still far from infallible. So drivers can't be allowed to become distracted or drowsy, or to otherwise endanger themselves.

More Goodies

The CT6 is loaded with other high-tech amenities. There's night vision to help prevent deer strikes, an active rear-wheel steering system to help with cornering and a 34-speaker Bose Panaray premium audio system. The car also has a teen-driver mode that locks in all the safety systems and allows parents to monitor driving behavior, limit the volume of the car's stereo and set speed alerts.

MORE: Android Auto FAQ: Everything You Need to Know

My favorite feature is the video rearview-mirror system. It does an excellent job of all but eliminating blind spots. It takes some getting used to, because you get a field of view that's about four times greater than that of a standard rearview mirror. A glance in the video mirror shows you vehicles that are not only behind you but also off to each side. I found the system accurate and helpful, although on a sunny day, it created more reflections than I would have liked on its screen.

My favorite feature is the video rearview mirror system. It does an excellent job all but eliminating blind spots.

To keep the image clear and in focus, the rear camera has a high-pressure washer system and a hydrophobic coating. If you find that the wide-angle view behind is not for you, you can switch it off and use the conventional rearview mirror with the flick of a switch.

Super Cruise vs Tesla Autopilot

If you're wondering what's to prevent a Super Cruise-equipped Caddy from having a Tesla-like fatal accident, there are several differences between the two company's systems.

In spite of some misleading press comparisons, Tesla's Autopilot system is not comparable to GM's Super Cruise. Autopilot is not a truly self-driving system, because drivers are supposed to keep at least one hand on the wheel. Tesla's system does not have any LiDAR mapping to rely on, and the system is not restricted to particular highways. GM's Super Cruise, by contrast, does not require the driver to keep a hand on the wheel, and it comes with the high-resolution maps needed to confidently drive itself down the highway.

MORE: Apple CarPlay FAQ: Everything You Need to Know

More important, by limiting the use of Super Cruise to highways that don’t have cross traffic, GM has eliminated situations like the one that tragically killed Josh Brown in a Tesla Model S. This is not to say that there won't be potentially dangerous scenarios in which drivers will have to retake control of their vehicles. Pedestrians and animals still wander out onto highways, and human drivers still cut off other cars. However, GM's driver- awareness system — which Tesla lacks — should help maintain driver focus.

Bottom Line

To beleaguered drivers fed up with monotonous, fatigue-inducing miles of highway driving, Super Cruise represents a liberating moment. To those who fret about a dystopian future in which the machines control humans, this development is a troubling turn of technology. Nevertheless, there's more to come.

By the end of the year, Audi is planning to introduce its Level 3 traffic jam pilot package that will let drivers abdicate control of their cars when going slower than 37 mph. Audi calls this the first "conditional automated driving" system. The company's system, by definition, does not require the driver to pay attention, while Cadillac's requires driver attentiveness.

On one stretch of I-95 where I was letting the CT6 do the driving, I noticed a vehicle riddled with LiDAR protuberances and video-camera bumps. It turned out to be an Apple mapping vehicle. I waved to the driver as the Cadillac sped right by.

2018 Cadillac CT6 Platinum: The Vitals

Price as Tested: $85,290 MSRP (including destination charge)

Engine and Drivetrain: 3.6-liter V6 with eight-speed automatic transmission and all-wheel drive

Fuel Rating: 18/27 mpg city/highway

Connected Car System: GM CUE 2.6 system with 10.2-inch touch screen, including Android Auto and Apple CarPlay support and a 12-inch driver instrument LCD cluster

Safety Technologies: Collision avoidance (emergency braking) with night vision, lane-departure warning, blind-spot warning, rear cross-traffic alert, adaptive cruise control with auto stop and go

Driver Assist Technologies: Super Cruise highway-driving system, rear camera mirror, surround vision, automatic park assist, rearview camera

Credit: Cadillac

John R. Quain

John R. Quain has been reviewing and testing video and audio equipment for more than 20 years. For Tom's Guide, he has reviewed televisions, HDTV antennas, electric bikes, electric cars, as well as other outdoor equipment. He is currently a contributor to The New York Times and the CBS News television program.

  • muka
    Kudos to the pr people for making you think you were in a self-driving car. Go for more Demos in more cars, especially from startups, and you'll get a richer picture of where the state-of-the-art is. Not to take away anything from Cadillac but this is not a self-driving car.
  • jto654
    Wow you obviously have not driven a Tesla for any length of time or were quoting from the Cadillac marketing people. To say that a system that allows you to take your hands off the wheel but still have to constantly pay attention to the road is more advanced than Tesla's system (that also let's you take your hands off the wheel but you do have to touch every few minutes - to prove you are paying attention) is a pretty big exaggeration. Since Tesla can steer on roads other than the 130,000 miles of mapped highways, I would call Tesla's system more advanced. If Cadillac said you don't have to pay attention at all, then it would win. But a simple symantec of having to touch the wheel less but still prove you are paying attention is really just 2 different schools of though on proving you are paying attention - touch the wheel vs a face tracking camera (which Model 3s supposedly also employ - but they are employee only vehicles right now). But it is great to see Cadillac and Audi also throwing their hat in the ring with an actually released car.