The details of Euro 6 emissions regulations are still under discussion in Brussels, and exactly how truck engine manufacturers will respond is unclear. Companies are working on the assumption that they will focus on big NOx reductions - possibly from 2g to 0.4g per kWh - to achieve a level of equivalency with US standards when they come into effect in 2013.rnThe uncertainty isn't helpful. Manufacturers must continue to make their vehicles more fuel efficient - truck buyers are expert scrutinisers of purchase prices and running costs. But finding the right balance between economy and the price of aftertreatment is complex.rnOne of the key technologies is selective catalytic reduction (SCR), basically injection of AdBlue aqueous ammonia into the exhaust stream to turn NOx emissions into N_2 and water with the help of a catalyst. Because it means dosing the exhaust with droplets of additive that must be replenished regularly, it does not enjoy natural popularity.
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