ScanGauge 2 has changed my life. You will NOT regret your purchase of this piece of tech.
I don't know why I didn't get one sooner, today was my first full day using it, put 130 miles on it, and I have to say, I am blown away. Knowing so much about what is happening with the vehicle is essential if optimum efficiency is what your after. I can't overstate this, the device will net you at least 5 mpg better if not more by virtue of knowing what you are and aren't doing right with the engine and your driving style.
There is a 5 day backlog on units. It is posted on the website in big red letters, but this must be a recent surge due to the ECOMOD explosion that is occuring. It is well worth the wait and will easily pay for itself in a month or 2 depending on how much driving you do. It's genius!