I did not realize that Z2 have also been reformulated. Here are couple of quotes from Autopia forum:
"The new Z2 has been out for a while now, the newer Z5 formula began shipping this Spring. The Z2 is now pinker than before and the Z5 is almost orange or tan, compared to the previous cream color. As far as results go, well, I've used Z for a few years and I can tell a difference between formulas, but it is very slight. The newer Z5 applies easier than before and has a fantastic shine, more similar to the older Z2. On the other hand, the new Z2 seems to really bump up the gloss when used in multiple coats, i.e. with ZFX. If you're still using the older formulas, don't worry, the changes are so slight, most wouldn't even notice, other than the change in color. The durability and gloss does seem to last even longer, if that's possible, but it's hard to tell really. Just use up your current supply, then look forward to ordering the "newer" stuff. I've still got both versions, and regardless of which you use, you in for a fantastic shine with unsurpassed protection! "
"I've heard that the new Z5 tends to darken the paint color a little more which gives it more of a "carnuba" (warm) look. Have you found that to be true?"