It still has flaws, but if General Motors deploys it to other vehicles besides the CT6 it could instantly become the unrivaled leader in semi-autonomy.

It's more limited in where and when you can use it than Tesla Autopilot, but it consistently makes the driver feel safer and in better hands than rival systems.

You'll want to buy the autonomous model Mack Hogan | CNBC

I tested Cadillac's new Super Cruise autonomous driving system in a brand new 2018 CT6, and I'm convinced it's way better than anything else on the market, including Volvo's Pilot Assist and, yes, even Tesla Autopilot.

What is Super Cruise?

Cadillac's Super Cruise was better than Tesla Autopilot in our tests. Mack Hogan | CNBC

The foundation of Super Cruise is an extensive array of LIDAR maps that cover most of the major highways of the United States. Teamed with the car's radar and cameras, the maps allow the CT6 to have situational awareness that bests any other commercially available system. Super Cruise, unlike competitors, allows you to take your hands off the wheel. Once you engage the system, a light bar on the wheel turns green to tell you it's safe to remove your hands. In fact, you're best keeping them off the helm if you don't want to disengage the system by nudging the wheel. You're supposed to keep your hands on the wheel when using Autopilot and Pilot Assist. Of course, this is still a rudimentary semi-autonomous system, and therefore the driver remains entirely responsible for the car's actions. That's why a small camera mounted on the steering column monitors your eyes to make sure you're paying attention. If Super Cruise makes a mistake — it didn't make a single one in my tests — the onus is on you to correct it.

Why it's a game-changer

That green light means you can take your hands off the wheel. Just keep your eyes on the road! Mack Hogan | CNBC

The truth is that semi-autonomous technology in competing systems can't handle complex situations, even if you're allowed to activate it. It nurtures a strange relationship where you never know if the car actually knows what it's doing, so you're constantly stressing over whether the car can handle the severity of the upcoming curve. That isn't the case with Super Cruise: Every road you use it on has been pre-scanned and will work with the system. In hundreds of miles of testing, Super Cruise never failed to negotiate a curve or slipped out of lane markings.

The 2018 Cadillac CT6 Platinum Mack Hogan | CNBC

Instead, Super Cruise knew when it was about to encounter a complicated off-ramp or interchange. It flashed the light bar red, vibrated the seat and handed control back to me. If I had failed to take control, it would have come to a stop in its lane and contacted emergency services. This is important, because it was never unclear to me as the driver whether or not Super Cruise could handle the situation. When the light bar is green, it perfectly negotiates every normal situation and ensures that you're watching out for abnormalities like busted tires or garbage in the road. When the light bar flashes red and turns off, it doesn't know what to do and expects you to immediately take hold of the wheel.

The drawbacks

Behind the wheel of the 2018 Cadillac CT6 Mack Hogan | CNBC

First, it's technically more limited than rival systems from Tesla, BMW, Volvo, Mercedes and Audi, even though I liked it more. Super Cruise works exclusively on divided highways that have been mapped by Cadillac's mapping partner "Ushr." It won't engage in foul weather, and it has no interest in construction zones. Simple freeway driving is all that Super Cruise will handle, while other cars will work elsewhere, even if they don't work as well. I had a few other problems, too. I encountered a few stretches of road where Super Cruise refused to engage even though the road was mapped — I had Super Cruised it days before — and there was no dialogue to tell me what the problem was.

The 2018 Cadillac CT6 Platinum Mack Hogan | CNBC

I also spoke with another journalist from Los Angeles who got Super Cruise to engage only a handful of times throughout his week-long test. If you're considering a CT6 Super Cruise, ask the dealer to let you test it on the highways you drive often. The system could also do a better job handing over control when it's coming up on something like a toll booth. The car knows it's coming for miles, as it's all mapped out, but when it gets to the spot where it wants you to take over, it instantly starts flashing and vibrating and shaking. A simple warning like, "Please return your hands to the wheel and prepare to take control," when it knows a human driver is needed soon would go a long way toward making Super Cruise a little less stressful.

Final thoughts

The 2018 Cadillac CT6 Platinum Mack Hogan | CNBC