The Unknown Driver

The four-lane highway stretches out in front of us in long, graceful curves as the car glides effortlessly over the road, barely touching the pavement it seems. Nina is sitting in the front passenger seat. I'm directly behind her. We pass huge, box-shaped warehouses that sit glistening white by the docks along the bay. The road rises in an overpass that arcs around the bay spread out before us. The azure water shimmers as if every molecule were alive.
"How beautiful!" I say to Nina. She nods in agreement. A pure white bridge arches over a river. My breath is taken away by the vision of a perfect city cradled on all sides by shoreline.
Then I notice the driver's seat. There's no one behind the wheel! I panic.
"Who's driving?" I ask Nina.
"Don't worry about it," she says. I do worry about it, though. The more I worry, the more the car gets out of control It veers wildly back and forth across lanes suddenly filled with rush-hour traffic. Tires screech, horns scream. The dream ends.

What do you think this dream means?