Many of the operating conditions that make diesels powerful, efficient and cleaner allow them to produce oxides of nitrogen or NOX. NOX can be a dangerous air pollutant at high concentrations causing breathing problems. However, many of us want a TDI because we live in the wide open spaces where NOX dissipates before it causes any harm. IMHO greenhouse gasses like CO2 are a much greater global threat. I would trade a little NOX for a diesel that produces less soot, makes more power and gets better mpg. EGR is used to lower NOX but it doesn't make a diesel run better. So shame on VW for trying to give us something we want to drive.
