Your street look very bright at night, or is it all from the IR lights?
When I tested my Z5, I had more success getting sharp images if I lowered the gain further. You can always open up the iris accordingly to compensate. I kept the iris at about 80-90 and it gave me enough DOF that getting the right focus was easy. I had the camera fully zoomed in, shutter speed at 1/1000th, which left everything but the license plate and lights totally dark.