When we purchased two 2012 LTZ Sonic's, one month apart; they had just recently been released for sale. They were hard to find then, and that hasn't seemed to change over two years later. We liked the LTZ trim level because we were used to optioned-up prior vehicles; but were looking for the same in a smaller more fuel efficient vehicle. The reason that they are more difficult to find is that there are more lesser cost models produced to satisfy the demand of the targeted sales demographic, which translates to the younger, sometimes first time vehicle purchaser, that the manufacturer perceives as maybe less affluent.
What the manufacturer doesn't realize is that there are consumers that appreciate the ability to purchase a quality smaller fuel efficient vehicle, without giving up some some of the features/options that are more frequently found on higher cost vehicles.