It's not just the arrows, (which are great), it's the extra antennae pointing rearward and the triagulation between it and the front one. When I'm out on the road at night in a rainstorm, or just really dark, I want to know exactly where the trooper is. I want to know when I'm past him, if there is another one ahead (or behind), how many separate sources, etc...
You cannot touch a V-1 w/ concealed display right in your gauges/line of sight. Read the independent tests, like these guys:
http://www.guysoflidar.com/