Here's my first with the PHV... Just Drive It This was my very first drive with the ScanGauge connected to the 2012 Prius PHV. I attached it to my filming rig with a camera, then covered them all with a box to block out all the external light. That meant I couldn't see any data until watching the video capture afterward. So, I was able to "just drive it" without any influence. The first thing I noticed afterward was the age and generic nature of that aftermarket gauge was inaccurate reporting of travel speed. Darn! It looks like the gauge is under-reporting by 3 MPH. Oh well, maybe there will be a new version available later for owners like me. That data isn't needed for my driving anyway, especially since I have a HUD (Heads Up Display). The next observation was engine RPM. It's accurate, but slow to refresh and reports when the engine motion has come to a halt... not when fuel is actually cut. Fortunately, the PHV model has an EV indicator, informing you exactly when that fuel consumption has ended rather than waiting for the fuel-less engine to stop spinning. MPG an unknown. Since I couldn't see the gauge while I was driving, I'll have to wait for future drives on the 70 mph highway for comparison. FWT (coolant temperature) is priceless in an fashion. You could clearly observe how I entered the highway with the system still cold, how long it took to warm up, and how long that warmth was retained once returning to EV driving. For me, I especially like seeing the low RPM and high MPG while traveling at high speeds. The values themselves are revisions to the system since the early model PHV. That one drained the battery-pack faster, not taking advantage of the engine as much as this one does. This results in an overall higher efficiency and provides more opportunity for EV later. Remember, while in HV mode, the EV range will rise due to the engine running and regen opportunities. .