Hey Mike, what colour was it? I saw one about 2 years ago also with dealer plates parked at a Nissan dealer. At the time I didn't know anything about Japanese cars, and I guess I still don't
But my friend owned a 300Z twin turbo so he knows tones about Nissans. He was sticking his head under the car and feeling for stuff, afterwards stands up and says "yup, it's a real skyline" The one we saw was white.