Other than embarrassment, why on earth would the engine maker oppose a method that makes its engines run cooler and with less fuel?

FORBES: Institutional Stupidity, III

Because hydrogen can clean the exhaust right from a cold engine start, the plasma reformer method is 20% to 50% more efficient at reducing NOx than other clean-diesel technologies, allowing less unburned fuel to pass through in the process.

FORBES: Clearing the Air