This is just an idea that perhaps someone will test.
(Is ther a better place to post this?)
Dissolve exhaust gas in water and see how it does as an electrolyte:
CO2 + H2O ? H2CO3 (Carbonic acid) + dissolved CO2 (This is a weak acid)
C + H2O = CO (burns) + H2
Dissolved O2 (O2 will displace air: a good thing)
Thats about it; if you have a 3 way cat.
Without you also get:
NOx + H2O = 4 HNO3 (nitric acid) via a long process that includes HNO2, HNO3 and NO
CO + H2O = HCOOH (formic acid) + dissolved CO (This is a weak acid)
Unburned HCs + H2O =

(Didnt someone test a mixture of fuel and water in a cell and get good results?)
You will also get a small bit of hydrogen sulfide which dissolves in water to make a solution that is weakly acidic.
Perhaps this devil's brew is by some fluke the ideal electrolyte and gives great gass production and cleans up our exhaust a little!

What exactly the gas will consist of is a damn good question!

Certainly H2 and O2.
Perhaps CO (burns)
Possibly Nitrogen.

You may end up with carbon on the electrodes, which may or may not be good.
The gass hopefully will contain CO. (burns)
A simple test by bubbling exhaust through a bucket of water and using it in a cell would be interesting.
No idea how fast the solutes will be used up or how much of each will be in solution.

So what do you think??
http://mattson.creighton.edu/H2S/H2S_Info.htmlhttp://wiki.answers.com/Q/Is_carbon_monoxide_a_acid_or_alkaline_solutionhttp://en.wikipedia.org/wiki/Carbon_monoxide#Atmospheric_presencehttp://en.wikipedia.org/wiki/Nitrogen_oxidehttp://en.wikipedia.org/wiki/Carbonic_acid