"Still The Best Water Fuel Kit In 2009..."
By far the easiest-to-follow guide I came across - my own experience says you should set aside maybe half a day to buy the parts and get it fully installed.
This is the only guide that assumes absolutely no knowledge of cars. Impressively, my support ticket was responded to in under an hour (although it could take a little longer on weekends), and there is an Unconditional 8 Week Money Back Guarantee.
Best of all, the technology required is readily available and cheap - I was able to access all the parts needed for well under $50. Given that its proven to increase fuel efficiency by as much as 40%, you could well recoup your investment in under a week.
Installation works with any gas or diesel powered car, van, truck or SUV. Aimed squarely at car "novices", and still my top pick for 2009.
June 2009 Update:
there is now a promotion running on the site, and it is available for $97 for a limited time, instead of $297 - as such, I recommend ordering sooner rather than later. Good for you, bad for me. I paid $297.
The Verdict:
Fast and easy setup; works for complete car novices; proven fuel savings of upto 40% - my top pick