>This catalyst causes a reaction on it's  surface which converts nasties
(oxides of nitrogen as >monoxides of carbon, etc)  to their fully oxidized
(and less harmful) states.

>So then why would it be a factor in fuel economy?

Because when they impound your vanagon for noxious emissions, your mileage
goes to zero, and as the mileage goes to zero, so do the miles/gallon.

Dave in KC (who missed last Friday's session)