The automaker teamed up with the Fraunhofer Society to build a "driving" (it's actually more just sitting) simulator to conduct tests on subjects to see how they react to different stimuli. The simulation recreated the feeling of riding in a car while it drives through city streets at night using large projections on the wall while displaying information on the "windows" of the vehicle.

The researchers then studied the brain activity of 30 millennial subjects from Hamburg, San Francisco and Tokyo as they were shown ads and social media updates and asked to perform random tasks. Unsurprisingly, the EEGs of the riders showed increased arousal (get your head out of the gutter) when bombarded with information and asked to execute certain activities.

While this seems like a "well, duh" moment, the reality is that automakers need to figure out what people will do in their car when they stop driving. Both Audi and BMW are already trying to figure that out, because it's not like any other situation we currently encounter. Public transit is, well, public; driving with friends is a social experience. A single rider in an automated vehicle day after day, that's something new.

As a luxury automaker looking toward the future and wanting to continue to sell cars, it's important for Audi to determine what type of environment it'll create -- even if some of those potential customers will never actually be behind the wheel.

Autonomous cars will help us reclaim lost time. Audi said that on average people spend 50 minutes per day behind the wheel. What will we do with that time? Will we watch TV, work, connect to social media or something completely different? That's what Audi's trying to find out and in the process making sure it doesn't create an annoying environment.

During Audi's Tech Summit, I got a chance to do a less intense version of the test conducted on the millennials. I didn't wear a skullcap with wires hanging every which way. Instead a heart rate monitor was attached to my wrists and fingers. I sat in the "car" with a few other journalists, and we went for a short "drive." The demonstration went from relaxed to slightly annoying when I was asked to count the number of times certain letters appeared while being bombarded with ads on the displays.

My readout showed a slight arousal blip during the test. That's not that surprising: My day usually involves dealing with a ton of data and distractions while writing. So I chalk it up to what's normal for me. But I did start to reach for my phone (they asked us not to do that) out of habit. Not doing anything is an odd feeling in our connected world. But doing too much is also not healthy. Audi and other carmakers need to find a happy medium.

Melanie Goldmann, head of culture and trends communication at Audi, said in a statement, "The results show that the task is to find the right balance. In a digital future, there are no limits to what can be imagined. We could offer everything in the car -- really overwhelm the user with information. But we want to put people at the center of attention. The car should become a smart membrane. The right information should reach the user at the right time."

The 25th Hour is a nice marketing term. Audi is planning on making self-driving cars just as luxurious as its current cars, just in a different way. Regardless of what finally ends up in our robot-chauffeured vehicles, carving out more free time in our hectic lives is wonderful. It'll just be interesting to see how we use it.

Correction: An earlier version of this article used "EKG" in reference to brain measurements. The measurement of electrical activity in the bran is an EEG. EKGs are the measurement of a heart's electrical activity.