When driving on 151 from Madison to Platteville WI when a triangular UFO was witnessed. I was alone in the car. It was foggy that night. Heavy overcast. Visibility limited to 1/2 mile in the valleys. When about 5 miles outside of Dodgeville WI lights were observed about 1 oclock in front of the car. The craft was large. It was very eerie also. There were three lights on the undercarriage of it. No light was seen in the center of the craft. The craft was jet black. It was a 100 feet or more in subtended length. A point of the triangle faced the car as it approached the craft hovering about 50 feet above the ground, 150 feet off the side of the road. The craft then rotated and started to follow the car on the side of the highway. The craft stayed with the vehicle for about 10 seconds until a hill got in between the craft and the car. Of course I started to freak out when this started occurring. I guess it's notable that this wasn't the first time I've seen a triangular craft, and not the first time witnessing one when driving on the highway. I guess it's also notable that all the sightings so far have been equally scary. I started kind of crying, partially in anger, partially in fear, as it started to follow me. It was really scary. The hair definitely stood up on the back of my neck, and felt a really hollow fear, I guess trepidation mixed with anger is the best explanation. When the car passed the other side of the hill about 30 seconds later I had speed up to 100/110 mph, and the craft was not there. I checked the time, and of course no time was lost. Nothing special about the sighting, but I guess I thought it was worth reporting.