Travelling at about 90km/h on a Nevada highway, the big rig's driver looked like The Thinker, with his elbow on the arm rest and his hand on his chin. No hands on the steering wheel, no feet on the pedals, Mark Alvick was in "highway pilot" mode, the wheel moving as if a ghost were at the helm.
Daimler Trucks North America says its "Inspiration" truck, the first self-driving semi-truck to be licensed for public roads - in this case any highway in Nevada - is the future of trucking.
The vehicles still need drivers, but they might be called "logistics managers".
"The human brain is still the best computer money can buy," said Daimler Trucks North America CEO Martin Daum.
Although much attention has been paid to autonomous vehicles being developed by Google and car companies, Daimler believes automated big rigs will be rolling along highways before self-driving cars are cruising around the suburbs because the open road's lack of red lights and pedestrians make for a less complex trip.