Well, I received and installed the Garmin Mechanic and ecoRoutee HD module. I installed it and after around a half minute to do the first handshake with the Garmin Nuvi, all is well.
The info is only a few taps away on the menu. So far, it seems very interesting. Not sure why I would want to know engine manifold pressure at the moment, but the info is nice to be sure. There are 5 gauges that you can customize with various different information readouts. After using this for a few days, it just hammers home that there are so many different sensors on a modern vehicle these days...it is nice to access the info whilst driving. So far, I am liking that I can monitor battery voltage in real time.
On the plus size, it will also tell you problem information on the GPS via diagnostics. Something I hope to not try out anytime soon. I bought a stand alone code reader for my Van that showed a check engine light for a few weeks. I couldn't figure it out. The unit told me that I had a faulty gas cap that was not properly sealing. Replaced the gas cap, and saved a bundle by not bringing it into the garage. It is nice to now have a built in dedicated unit mated to the GPS for these instances.
As for the ecoRoute HD part, well, that is a bit interesting and disheartening. You tell the unit your gas milage, gas price, and other parameters, and it will calculate how much it costs you to get there in real time. For instance, it cost me 23 cents to drive to work each day. The unit will also tell you when your saving on fuel by doing good driving habits. The unit also has an eco-game mode which I haven't tried yet.
Personally, I like having all that info at your finger tips. Not so concerned about the eco info. One thing I did notice, when I have the info gauges up, when the unit auto powers down, it will splash your fuel cost info for a few seconds before shutting off.
all in all, not bad. An interesting toy to play around with. This will only work on Garmin units with built in Bluetooth.
Here is a video review to give you a better idea of the add-on.