Honda developed a system that basically makes its own DEF in real time:
Honda's engines have a catalytic converter that filters out enough nitrogen oxide (NOx) emissions to meet California's new standards -- the most stringent in the nation -- due to come into effect in the state next year and nationwide in 2009. Unlike other diesels that will meet California's standards, such as a Mercedes-Benz (DCX ) BlueTec expected to go on sale in late 2007, Honda's doesn't require a separate tank of urea, an organic compound that helps absorb NOx but needs to be replenished occasionally. Instead, its diesel converts some of the NOx into ammonia, then recombines that with what's left of the NOx to make relatively harmless nitrogen. Honda says the technology will reduce exhaust emissions to levels on a par with gasoline engines. "The Honda system is quite elegant," says Christopher Richter, a Tokyo analyst at CLSA Asia-Pacific Markets.
Does anyone know why Ford did not go this route?
Honda's Green (Diesel) Machine