HTC Zara is actually HTC Desire 601, according to the usually very reliable evleaks. An official render of the phone has already leaked once along with a bunch of specs.
HTC Zara will ship as the Desire 601
— @evleaks (@evleaks) August 30, 2013
HTC Zara a.k.a. Desire 601 will supposedly pack a 4.5″ qHD display and will run on the Qualcomm Snapdragon MSM8930 chipset with two 1.2GHz Krait cores, 1GB of RAM and an Adreno 305 GPU. The rumored specs sheet continues with an 8MP camera, 8GB expandable storage and Android 4.3 Jelly Bean with Sense 5.5 UI on top of it.
Recently we saw another unannounced HTC model leaking, which according to the latest rumors is codenamed HTC Zara mini. It will probably have the same internals as Zara/Desire 601, but downgrade the display to a 4.0″ WVGA unit and the rear camera to 5MP resolution.
HTC Zara mini
An educated guess would be that both HTC Zaras are going to be unveiled in September alongside the HTC One Max.