I only started getting 4-5 mpg more on my truck, so it was a big let down for me as well.
You must not be living right. My super duty now only needs water (or I can just use dirt in a pinch) to run and it tows better than when I had to spring for diesel. This all in exact synchronicity with receipt of my 280AI!
I'm thinking about getting another one done just to see what happens. Not sure that I could handle it.
