Not directly relevant to the TCH, but...

I have been using the fugly ScanGauge-I since last March and I keep it right on top of my dash. Yes, it looks tacky. Yes, I have to be very careful to put the sun shade up every time I leave the car in the summer. But it's convenient and I wanted to put it as close to my line of sight as possible so that I don't have to take my eyes completely away from the road to glance at it.

Wendy- the ScanGauge plugs into your OBD-II port and allows you to monitor a range of operating parameters in real time as well as track averages over the course of a tank, day, or single trip. Beyond that it also functions as a code reader in the event that your "check engine" light goes off. As far as fuel economy is concerned, this is mainly geared at people like me who drive a car without a sophisticated trip computer. I can't even begin to tell you what that feedback has done for my driving. I believe it is also used by people who do have trip computers but don't find the OEM feedback to be completely satisfactory. Not only does the SG give you more options, but it allows you to tune the calculations to match your calculations at the pump, reducing discrepancy between what you think you are getting and what you are actually getting.

To each his own. I have no idea what kind of feedback a TCH gives you so it's tough for me to say what it would add to your experience.