Attending to One Thing and Lose Another

A newly release requirement of “manufactured diesel trucks spew out less soot” commenced this year is arousing a paradox for truck fleets: “These new-generation trucks are cleaner than older-generation vehicles, but they get worse mileage.” Driving by the stricter regulations of emissions, diesel truck manufactures are suffering from developing new kinds of engines that exhausts less soot such as nitrogen oxides and carbonic oxides. To meet with the new standards, “diesel trucks manufactured after January must produce 50% less nitrous oxide and 90% less particulate matter than emitted by previous-generation trucks”. However, the problem is that with less exhausting, means more fuel burning. The average mileage of previous-generation trucks is about 9 or 10 miles to each gallon of diesel fuel while new engines designed to meet the more-stringent federal mandate on truck exhaust get about one mile less to the gallon. “That may not seem like much, but it all adds up for large fleet owners that operate trucks crisscrossing the country”. To tackle the paradox, the spokesman of EPA (Environment Protect Agency) has commented that “the agency had anticipated some fuel-mileage loss with the new engines. At the same time, companies are telling us that these new, clean engine systems have maintained or improved fuel efficiency through all sorts of innovations”. However, whether the improved fuel efficiency is going to offset the impact of the loss in mileage has been doubted.
Here we are encountering various kinds of externalities, and when this happens, there may be some conflicts among these externalities. To meet the social benefits, we have to develop an engine that is friendly to the environment. At the same time, it means a loss on mileage of the engine, which affects another externality, the scarce petroleum. If the mileage of all American autos was reduced one mile, how much more oil would be in need? The only way to balance between these externalities is to compare the benefit and cost of fewer exhausts and reduced mileage. Anyway, when dealing with various externalities, we certainly do want to attend one thing to lose another.