From 2010 onward, all new truck engines must achieve tough, near-zero limits for nitrogen oxide (NOx), a chief ingredient of smog. Virtually every truck maker besides Navistar chose to use an add-on system that has been approved by the EPA, while Navistar has chosen to invest hundreds of millions of dollars to refine an engine that produces minimal NOx in the first place.
If Navistar's engine works - the company recently submitted test results for the latest version to the Environmental Protection Agency for certification - it could be the simplest, most elegant solution to the vexing engineering problem of how to reduce smog created by diesel truck exhaust.
