Ask a dozen people to define "luxury" and you'll get a dozen different answers. Maybe even more than that. But at its core, luxury is about having the means to do what you want, when you want. That's what Mercedes-Benz is attempting to deliver with its fully-autonomous F 015 Luxury in Motion concept.

Yes, it's still a car. It has wheels and tires and seats and a steering wheel. You can still drive it, but why would you? It's an opulent autonomous appliance, and as any king or sheik will you tell you, the ultimate four-wheeled indulgence isn't driving, it's being driven.

To that end, it's positively massive. The F 015 is over 17 feet long with a wheelbase of 142.1 inches – almost a foot longer than the new Maybach – and rides on 26-inch wheels. The chassis is a combination of aluminum, high-strength steel, and carbon fiber reinforced plastic, which makes it around 40 percent lighter than a current S-Class.

Engines are noisy and unrefined, so Mercedes ditched internal combustion in favor of a hydrogen-electric hybrid drivetrain. The F 015 isn't about power, it's about wafting, so output is minimal (272 HP and 148 pound-feet of torque), but it's enough to get the sedan to 60 MPH in around six-and-a-half seconds, reach a top speed of 120 MPH, and drive for around 120 miles on electric power alone.

But none of that matters when you look inside.

When the driver walks up to the car, it recognizes either their phone or smartwatch and unlocks. The four suicide doors open to 90-degrees and there's an eyeful of high-end appointments, from walnut wood veneers and white nappa leather. But the four rotating lounge chairs are what makes it a self-driving cocoon for the elite.

Each chair swings out when the doors are opened and then swivel inside where passengers have access to six displays that form what Mercedes calls a "digital arena". You can swipe and poke at each, but they also use eye-tracking and gesture controls when physically touching something is just too much to bear. Everything is controlled this way – from the climate to the stereo – with a head-up display using augmented reality to show what's happening in the outside world.

Or not. A projector can display landscapes like forests, lakes, and mountains on the sides, all of it synced to the speed of the car to avoid motion sickness, and a "maneuver blinking" function glows to let the rear-facing passengers know when there's bend or abrupt braking coming up.

There are no mirrors or a license plate (it's replaced with a QR code, of course), but there are apps to have the F 015 self-park and pick up friends. When the driver wants to take control, the two front seats swing toward the front where a steering wheel extends out of the dashboard.

When the driver is behind the wheel, the exterior LEDs change from blue (autonomous) to white (manual) to let people outside the car know who/what is in control. Those LEDs also act as a way to communicate with the outside world, with the words "stop" or "slow" displayed behind and even the ability for the F 015 to audibly tell pedestrians to "please go ahead".

It's all part of what Mercedes envisions for the future of mobility, including special "safety zones" where only autonomous vehicles are allowed to be driven and where cities can consolidate self-driving cars to maximize street capacity.

Due date? About 2030, give or take a couple years.