What does the Scan Gauge give you that is not available with the NAV? Is it worth it?

 

I got the Scan Guage II to be able to monitor the battery voltage. I have lots of extra electronics (ham radios, scanners, cell amplifiers, broadband router, headrest LCD screens) and want to know when the voltage drops so I can get the batttery recharged or replaced to avoid a dead battery without warning. Is it worth it? I can't answer for you - It was for me.

 

ScanGage has about 20 different things it can display, plus you can clear the loose gas cap code and avoid paying the mechanic to do this.

The coolant temperature is one of my favorite readings. Got a cardboard block on the radiator and it's more detailed than the dash coolant temperature.