How do you break in a new 370 Z Nissan?

I bought a 370 Z with 4 miles on it of course I tryed it out and who is gonna try one out without red linning it I did it in 1st and 2nd and 3rd gear its a automatic but you can shift manual I wanted to see if it ran good now I'm reading baby it for the first 1200 miles that's a crock break them in like you want them to run I have done ever new car or truck like that and I get great reformance out of them so tell me if I'm wrong by doing this I now have over 300 miles on it and it runs better ever time I drive it... gonna put Mobile 1 full synthetic oil in it but don't know when the book says 7500 but they all say that I am gonna change it at 3000 it came with a high grade of oil in it but the book didn't say what kind I'm hopine its synthetic..