Single stage vs Two Stage vs 50% base/clear

[1960apache]

I keep forgetting to get other peoples input. I have been playing around with some panels. One with single stage black, another base/clear black and another single stage base, with single stage 50% clear mix. In pictures they look about the same, but in the sun, the single stage seems to just have more depth and gloss, but I am not sure if it is just my imagination.
What go me thinking is, I saw some reruns of American Hot Rod, and noticed that Boyd used single stage on most of the projects that were on the show, but they never say why?
Also, how much effect does the final grade of paper used to do the last sanding before painting? 400 vs 800 or ??
Let me know your thoughts and experiences. I have few projects that will be Black. Some black cars I see in the shows, just look like liquid black plastic and a mile deep shine, where others look good straight on, but looking down the side seems like they look "cloudy" is the only way to explain it!
Here is a good example of one that just looks what I am talking about, in the sun or florescent light, it looks great.