Judging from the similar model number (the Xperia Z is C660X), the upcoming Xperia C670X might end up looking similar save for the slightly smaller display. On the inside, it’s noticeably more muscular, though. The quad-core processor clock is bumped up to 1.8GHz, and it features Adreno 320 graphics. The C670X is also said to come with 2GB RAM, 32GB internal storage and a 13MP Exmor RS camera.
Now interestingly enough, the Xperia Blog was also sent a curious little render. It could be the C670X, or it could be just a placeholder image. The latter is more likely as that is actually the same image found in the Xperia Z guide.
Finally, expectations are to see the Sony Xperia C670X in the middle of 2013 with Android 4.2 Jelly Bean.
source: Xperia Blog