The main sticking point in getting diesel engines to pass California emissions has been levels of nitrous oxide (NOx), which are emitted at higher levels from diesel engines. Honda says that its new diesel engine will be able to meet these standards through the use of a new kind of catalytic converter. The newly developed NOx catalytic converter is able to generate and store ammonia, which is used to decrease NOx levels, on board the converter itself. This is different from the system championed by the only other companies that are currently selling diesels in the United States, Volkswagen and DaimlerChrysler, which combats NOx emissions using a technique called urea-injection. The EPA has been hesitant to approve this technique because it requires a refill every 10,000 and EPA regulations require emissions systems to function for 10 years or 150000 miles in order to be approved.
Should Honda achieve 50-state compliance, it would be a major accomplishment and will give the automaker a step up on the competition in a market where fuel economy is becoming increasingly important. Honda’s current diesel offerings in Europe and other areas are capable of achieving fuel economy ratings as high as 60mpg without relying on expensive hybrid technology, which makes for an appealing vehicle for people who have to commute a lot.