Car Mechanics is a UK based magazine that covers, er, car mechanics. Its aimed partly at the trade and partly at the kind of person who wants to service at home. I read it as a knowledgeless fiddler to be honest.
In 2009 they decided to feature the
WaterBoost system. If you read the website it announces more or less straight away that it is a "Hydrogen Fuel System" - basically HHO - IMHO.
Now they have featured it again. At the end of two years in a Vauxhall Omega 2.5 TD they have noted a slight improvement in emissions - from 2.92ppm to 1.76ppm which they put down to the WaterBoost system "steam cleaning" carbon from the cylinder heads.
For the all important MPG ? Well in terms of carefully controlled A-B-A testing, forget it. They include a graph of MPG.
(Apologies for quality I don't have a scanner).
Their conclusion is that there is no difference in MPG. I'm kind of seeing a decline in MPG for the period of the test myself (Mar-Sep 2010).
Anyway, I shall email the editor - I may mention EM.
(Background, the Omega 2.5 TD has the BMW I6 IDI Turbo diesel engine from the BMW 325TD without the intercooller of the TDS)