Engine Makers Raise Concern Over New Fuel's Energy Content

espite hopes that the next generation of diesel engines coming in 2007 would have the same fuel efficiency as current models, early concerns are surfacing that ultra-low-sulfur diesel fuel might actually reduce the new engines’ efficiency as a by-product of the way it is refined.

While some industry officials said it is too early to tell what effect ULSD would have on the engines, others said their experience had not shown that the fuel — which would be introduced nationwide in June 2006 — produced a drop in miles per gallon.

If ULSD does cause a decline in fuel efficiency, it would be outside the direct control of the manufacturers of the trucks and engines — which engine makers said makes them wary.