Alas, they didn't have reactors small enough for it and so we were forever deprived the sight of it cruising down main street.
In looking at it, I do wonder how well it would have handled. The lead shielded passenger compartment and the aerodynamic nose are both ahead of the front wheels. Would they have used rear wheel steering? Either way, with that configuration the Nucleon would have been an adventure to try to parallel park.
Also, is it my imagination of did they forget to include doors in the design? I wonder how you were supposed to get in and out of it?
The best information I could find about it was at SonicBomb:
Ford's engineers imagined a world in which fuel stations dotted along the highway, would wash your windscreen and then swap out your depleted reactor. The car's reactor was essentially the same as a nuclear submarine's, but miniaturized for automobile use. It would use uranium fission to heat stored water into high-pressure steam which could then be used to drive turbines, which in turn would both propel the car and generate electricity. The steam would then be condensed back into water and sent back to the steam generator in a closed loop.
The designers anticipated that a typical Nucleon would travel about 8000 km per charge. Because the power plant was an interchangeable component, owners would have the freedom to select a reactor configuration based on their personal needs.
Prototype 2 The passenger compartment of the Nucleon featured a one-piece pillar-less windshield and compound rear window, topped by a cantilever roof. There were air intakes at the leading edge of the roof and at the base of its supports to be used as part of the reactor's cooling system. An extreme cab-forward style provided more protection to the driver and passengers from the reactor in the rear, and to provide maximum axle support to the heavy equipment and its attendant shielding. Some pictures show the car with tail fins sweeping up from the rear fenders.