Yeah, for techies, this is the kind of gadget that's just too hard to pass up. I'm thinking very hard of doing a roadtrip tomorrow and comparing all the data between the the GPS (for distance), the cluster's trip odo and how much fuel it will take to top it off; thus the calculated gas mileage, versus what the ScanGauge shows the mileage and fuel economy to be. Hopefully all the numbers pretty much agree with each other. Here's a picture of mine mounted next to my GPS:

http://www.autocrossing.com/misc/junk/scanguage.jpg