At General Motors' technical center in Warren, Michigan, hundreds of volunteer drivers have tested real Cadillac Lyriq EVs.

They also tested other GM models inside a simulator.

The 360-degree immersive environment measures eye movement, heart stress and sweating.

GM uses it to study how human drivers respond.

It does not only study how the vehicle technology performs.

The simulator helps GM and other automakers test advanced driver assistance systems, known as ADAS.

These systems already offer features like automatic emergency braking and blind spot warnings.

They also offer lane-centering assist.

They let drivers go "hands-free" at certain times, mainly on highways.

Automakers expect these systems to become advanced enough.

Then drivers can take their hands off the wheel and their eyes off the road.

Sam Abuelsamid is vice president of market research at Telemetry.

He said "eyes off" is the turning point where consumers will pay for the feature.

He said it gives drivers back time because they no longer have to watch the road.

GM says its eyes-off version will be possible by 2028.

That is when it launches the next Super Cruise on the Cadillac Escalade IQ.

Abuelsamid said 2028 is a broad timeline for many companies.

They are targeting similar systems at highway speeds.

GM has sold Super Cruise since 2017.

It is a hands-free but not self-driving system.

It works on over 630,000 roads in the U.S. and Canada.

Tyson Becker is a GM executive director.

He said drivers can take their hands off the wheel and keep their eyes on the road.

This makes the commute less stressful.

More than 20 GM models now have the technology.

These include Cadillac, GMC, Buick and Chevrolet.

Becker said GM's goal is a next generation of Super Cruise that allows safe, eyes-off driving.

Predicting unexpected road scenarios is one of the hardest parts of developing autonomous technology.

A dog, deer or child could run into the road.

A construction zone could also appear suddenly.

Simulation, data collection and artificial intelligence help address this.

In GM simulations, drivers face computer-generated highway and city scenarios.

These include other "humans" and road signs.

Maureen August is a senior manager at GM Research & Development.

She said GM wants to cover anything customers could experience on the road.

GM watches heart rate, stress, eye direction and attention from a nearby control room.

One effective test is having drivers play Candy Crush, August said.

It engages them and then requires pulling them away.

After driving, participants are asked how they felt.

They are also asked whether the system was intuitive.

GM also looks at comfort, convenience, trust and how many seconds a driver needs to take full control.

August said GM wants drivers to respond effectively to alerts.

It also wants to let the vehicle do what it can when they feel comfortable.

Ford's BlueCruise is another notable hands-off system.

It is available on over 130,000 miles of certain North American roads.

Tesla calls its technology "Full Self-Driving," but it still requires human oversight.

No passenger vehicles in production currently offer eyes-off technology.

Some tech companies run autonomous robotaxi services in select cities.

Experts say regulatory hurdles remain.

Abuelsamid said there is little real regulation governing these systems today.

So automakers seek approvals state by state.

He said it remains to be seen where GM can offer its eyes-off system in 2028.

Automakers are racing toward advanced tech to attract consumers and earn subscription fees, he said.