Ok, this may sound less strange than the free energy post. Unless there's already a thread on Free Energy, maybe I should start one. There seems to be tons of info on this subject.

Anyway, this guy built a fit-in-any-car reactor that separates the O and H2 in water and uses it to improve the car milage about 20% on average.
Also, it seems to reduce carbon residue and emissions by almost 2/3rds.

Supposedly it installs in about 1-2 hours DIY or by a car mechanic in 1/2 to 1 hour. This seems to be the original inventor and he's keeping the price at a very reasonable level, so that you will make your money back very quickly.

http://www.savefuel.ca/