Most people underestimate the distance -if 40 feet turns out to be 80 feet once you have to angle the camera to get a more straight on shot, then the Z4E is the wrong camera. The Z12E is the most versatile over a bigger range of distances.
I am using OpenALPR, Plate Recognizer, and CodeProject ANPR and OpenALPR has been the most accurate. But each one has their pros and cons.
For me
OpenALPR pros include it captures more plates accurately and evaluates the entire video stream. The con is it costs like $15/month.
Plate Recognizer pros is that when there is a plate in the image, it does well at reading it. The con is after 2500 "reads" per month their is a fee that can add up quickly. Take a long time to dial it in so that you only send an image for a read that has a plate in it - every image sent counts toward the per month whether it is a plate or a camera trigger due to a shadow.
CodeProject ANPR pro is that it is free and will pick up any characters on a plate, whereas the other two are only IDing ones that match the format of the plate for the state. The con is it isn't as accurate, mine will bug out every couple of days and I have to restart it, and take a while to get it dialed in with BI.