Super Cruise, the “hands-free” advanced driver-assist system (ADAS) from General Motors, will soon be available on a lot more roads in North America. GM announced today that, later this year, the ADAS system will be able to operate on 400,000 miles of roads, including non-divided highways — which would essentially double Super Cruise’s current coverage in the US and Canada.

It represents a major expansion of Super Cruise’s capabilities at a time when US regulators are scrutinizing driver-assist features more closely and safety advocates are calling for more transparency, citing research that shows how new technology can create safety risks inadvertently.

Launched in 2017 with the Cadillac CT6, Super Cruise uses information from cameras and radar sensors embedded on the car, GPS data, and lidar mapping data collected by the company to allow for hands-free driving and, in some cases, automatic lane changes. It pairs this capability with a driver-monitoring system that uses an infrared camera to make sure the driver is paying attention to the road in case Super Cruise needs to hand back control to the driver.

Unlike Tesla’s Autopilot, which can be activated on almost any highway or road as long as the system spots visible lane markers, drivers are currently only able to use Super Cruise on divided highways that GM has laser mapped and approved for use. Up until now, that included just 200,000 miles of limited-access highways with concrete barriers dividing opposite lanes of traffic.

But, starting later this year, drivers of vehicles like the Chevy Silverado, GMC Hummer EV, or Cadillac Lyriq will be able to use Super Cruise on non-divided state and federal highways, which are sometimes called routes — main roads that connect smaller cities and towns. That includes the famed US Route 66, running from Chicago to Los Angeles; the Pacific Coast Highway, which runs along California’s coastline; the Overseas Highway, which connects Miami to the Florida Keys; and the Trans-Canada Highway, which transverses the country from east to west.

“Super Cruise is really helping redefine vehicle ownership and it’s really part of our wider path to autonomy at General Motors,” said Mario Maiorana, Super Cruise chief engineer, in a briefing with reporters.

For new GM vehicles built on the automaker’s “VIP electrical architecture,” the expansion will be available later this year and will be delivered at no additional charge via an over-the-air software update. Vehicles not built on the VIP electrical architecture, which include the Cadillac CT6 and XT6 and the Chevy Bolt EUV, will have to wait a little longer. GM intends for Super Cruise to be available in 22 models by the end of 2023.

On a parallel track, expanding Super Cruise is a step toward the much more ambitious Ultra Cruise, which GM has said will cover “95 percent” of driving tasks and will make its debut in a handful of premium vehicles starting in 2023. (GM has said that the two systems will “co-exist,” with Super Cruise available in more “mainstream” vehicles while Ultra Cruise will be reserved for the automaker’s luxury models.)

But there are still a lot of driving tasks that Super Cruise will not be able to handle. The system does not interface with the vehicle’s navigation system in a way that enables drivers to input a destination and let the car make all the necessary turns and lane changes.

In addition, Super Cruise cannot handle traffic signals and stop signs, meaning that the system will notify the driver when an intersection is 350 meters away (or 500 meters for non-VIP vehicles) so they can take control of the vehicle. And Super Cruise will not allow automatic lane changes on two-lane highways. In other words, it won’t cross either broken yellow or solid yellow lane markings.

What it will be capable of is handling the driving on a more broadly complex section of road types. For example, some sections of the Pacific Coast Highway are extremely curvy with only the bare minimum of space between opposing lanes of traffic. According to GM, the system’s use of high-definition maps of those roads will enable it to deal with every twist and turn safely and confidently.

“With a high definition LIDAR generated map, we can see out further beyond what the vehicle sensors can,” said David Craig, chief of maps at GM. “So we know the curvature of the road coming up, we know the speed we need to be able to navigate that curvature, and we’re in control of the speed longitudinally.”

Super Cruise is just a Level 2 system, based on the six tiers of vehicle autonomy as designated by SAE International and federal regulators. With Level 2, the human driver must be watching the road and ready to take control. The National Highway Traffic Safety Administration is now requiring automakers to provide data on crashes that occur with these Level 2 systems engaged.

Super Cruise options for around $2,200 for the Chevy Bolt EUV, but prices vary from model to model. GM isn’t planning on raising its prices for the system — but the automaker has expressed a desire to sell more features as monthly subscriptions as opposed to a one-time fee. (Tesla sells its Level 2 “Full Self Driving” beta system as a $199 a month subscription or as a $12,000 upfront fee.)

ADAS is becoming much more common in vehicles, with a variety of models at all different price points offering features like adaptive cruise control, blind spot detection, pedestrian alerts, and lane centering. While still Level 2, Super Cruise is more advanced, allowing drivers to take their hands completely off the wheel. And researchers are studying what happens to a driver’s attention when they are not in total control of the vehicle’s operations but are still expected to stay fully engaged in the driving.

Maiorana called the driver-monitoring system “the linchpin” of Super Cruise’s approach to safety, but he acknowledged that it was mostly a convenience feature as opposed to one designed to enhance the safety of driving.

“The benefit you get is the Super Cruise system itself handles the mundane portion of the driving: the steering, the deceleration, the braking,” he said. “I find when I’m driving Super Cruise, I am attentive, I’m watching the road, yet — and I am not a neuroscientist by any stretch — I get to my destination, feeling much more relaxed.”