In order for Cadillac to feel confident enough to introduce the industry’s first truly hands-free driving system to the public, the car company wanted to be sure it had enough data on the US highway system before it launched. How much data? Well, all of it.

To do this, Cadillac didn’t deploy a fleet of camera-mounted vehicles to record footage of the nation’s highways, like Google does for Street View. Nor did it rely on “fleet learning” like Tesla, in which many vehicles operating on the same software work together to build a more detailed map. Instead, Cadillac used vehicles equipped with high-powered LIDAR sensors to build a highly detailed map of the US highway system.

“we have mapped them within five centimeters of accuracy.”

“We went out and mapped 160,000 miles of interstate highways,” Barry Walkup, chief engineer of Cadillac’s Super Cruise, said in an interview with The Verge at the New York International Auto Show this week. “We have mapped them within five centimeters of accuracy. So that’s pretty impressive. This is the first use of a LIDAR map. You’re going to see more of that in autonomous [vehicles]. But this is the first application.”

“The car can see farther than the sensors on the car with the map,” He added. “With the map, we’re able to see about 2,500 meters ahead. So if we have a sharp curve, we can anticipate that, decelerate the car in order to maintain a g-level that we tune to take the curve.”

The new technology will be rolled out in Cadillac’s flagship CT6 sedan later this fall. Car buyers can expect to shell out $2,500 for the standalone option on luxury (sticker price: $66,290) and platinum models ($85,290). Also on luxury models, Super Cruise requires buyers to purchase the $3,100 driver assist package.

But the inclusion of the LIDAR maps is what Cadillac thinks will set Super Cruise apart from its competitors. Tesla recommends its drivers only use the semi-autonomous Autopilot system while driving on the highways, but technically the electric car company can’t do anything to enforce that. Cadillac has more control over how its customers use Super Cruise because of the mapping data. Super Cruise is restricted to only “divided, limited-access highways — highways with defined ‘on-’ and ‘off-ramps,’” the company says. In other words, no cities and no residential communities.

“We know where the car is because of the LIDAR map and the other data in the car,” said David Caldwell, product communications manager at Cadillac. “Therefore we have the ability to geofence it.”

But a map is only as useful as the road itself.

But a map is only as useful as the road itself. With construction and lane closures occurring randomly, it could be a problem if Cadillac’s LIDAR maps tell a different story than the conditions on the road ahead. To address this issue, Walkup said that Cadillac’s mapmakers are constantly checking the US Department of Transportation databases and deploying trucks to re-map road construction areas. And over-the-air updates are provided on an annual basis. “So you always have a fresh map,” Walkup added.

Cadillac wanted to restrict its hands-free driving feature to the highway because, frankly, it was a lot easier. No intersections, no pedestrians, no bicyclists, just long stretches of open (or congested) highway. While companies like Waymo (née Google) and Uber have self-driving cars deployed in dense, urban areas, and are working toward developing Level 5, fully autonomous cars that don’t require any human intervention, Super Cruise is just a Level 2 system.

Which means that drivers still need to keep their eyes on the road and stay engaged with the operation of the vehicle. They may be able to take their hands off the steering wheel and feet off the pedal, but if they turn their eyes away for more than 30 seconds, the car will know thanks to an infrared camera attached to the top of the steering column. Eyes closed? The car will know and start a sequence of alerts to get the driver’s focus back on the road. It can even see through UV-blocking sunglasses.

If you’re concerned about privacy, Walkup noted that the camera isn’t recording or storing any data. In other words, Cadillac isn’t interested in spying on you, just making sure you’re watching the road.

Cadillac tested a variety of alerts, like heads-up displays on the windshield and lights on the instrument cluster, before settling on something it calls the “light bar,” a strip of LED lights embedded in the top of the CT6’s steering wheel. The light bar will start flashing red if the driver is caught not paying attention. “It’s similar to what racing cars do,” Walkup said. “It’s information to the driver immediately. It’s right in your face.”

Regulators worried Super Cruise “may present an unreasonable risk of an accident”

Cadillac insists that safety is its motivating force with Super Cruise, but government regulators have expressed concerns in the past about the system’s ability to bring the vehicle to a controlled stop if the driver is unresponsive. Back in 2016, a lawyer with the National Highway Traffic Safety Administration sent a letter to General Motors noting this feature “may present an unreasonable risk of an accident occurring or of death and injury in an accident.” (Incidentally, that lawyer is now working for GM, according to Car and Driver.)

Walkup noted that other “systems in the marketplace” (read: Tesla’s Autopilot) do the same thing. In addition, OnStar (GM’s driver assist system) will contact the authorities to send help, if need be. That said, Mercedes-Benz is planning on introducing its Drive Pilot automated system this year that will pull the car over onto the shoulder of the highway before coming to a controlled stop. Caldwell said that Cadillac hasn’t mapped the shoulders of the US highway system, so it can’t make the decision about when it’s safe to pull over.

“You’ve got to remember that no cars in recorded human history up to this point have had any accommodations whatsoever for a totally unresponsive driver,” Caldwell said. “So when you think, wait a minute, stopping the car? That’s pretty awesome. No cars have done this at any point in time. An unresponsive driver is hurtling through time and space! Best of luck.”