Less than a year after announcing that US 2010 heavy-duty diesel-engine emission limits would be met using only exhaust gas recirculation (EGR)，aleading engine-maker has made a U-turn. Last month Cummins admitted that selective catalytic reduction (SCR) exhaust after-treatment systems using AdBlue - called diesel exhaust fluid (DEF) in the US - would be employed after all, in the interest of fuel economy.
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