Water injection has been around a long, long time. I posted earlier that there are some very good methods of making a simple system, quite economically.
This one is my own starting point:
http://journeytoforever.org/biofuel_...earth/me3.html
But I just found more on an Australian site that offers some added refinement:
It's a good overview article:
http://www.autospeed.com.au/A_107970/cms/article.html
Then they have this 3 Part DIY series of building the electronic and plumbing needed to make it work even better. Between the really simple one above and these 4 Aussie articles, I'll bet the potential for more economy and output could really prove out much better.
http://www.autospeed.com.au/cms/article.html?&A=1522
http://www.autospeed.com.au/cms/article.html?&A=1528
http://www.autospeed.com.au/cms/A_1539/article.html
By the way, there are many articles in there on aerodynamics, better air/fuel ducting and the main site offers DIY circuit kits for many of the projects they cover.