I just bought a new 2009 Honda Accord V6 with Nav and rear camera. I've only had it a few days and I'm already in love with it. But, I have one question. It has an automatic transmission and a tachometer. Of what use is a tachometer with an automatic transmission?

 

Not too much. If you were to downshift using the D4, 3, 2 positions it would help warn you if you're over-revving.

 

Good to keep abreast on how things are going under the hood.. you don't necessarilly use it for much, other than to be familiar with how fast your engine is turning at different road speeds and loads.. good to understand that for fuel economy purposes, and for diagnostics should something go wrong.. for example if you start pulling high revs but not moving any faster, you know you have an issue!.. but day to day.. not much use for an auto, even in a manual, i don't know anyone who refers to the revs to know where to shift.. one usually does that by ear/feel.