The Jetta TDI SportWagen could be a spiffy urea-free replacement for the old Benz wagon if you don't mind something smaller.

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The Jetta TDI has a 2.0-liter four-cylinder turbodiesel engine that operates efficiently enough not to require the new urea-injection technology that many larger, heavier diesels do in order to comply with exhaust emissions standards.

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In a 2011 ruling, Duffy wrote that while Yousef was awaiting trial, he had been trying to collect urea -- a component of urine -- and a type of watch that had been used in a detonator in the airline bomb plot.

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Otherwise, it's probably best to move with the times and deal with the occasional urea fluid fill-ups.

WSJ: Cars With a Higher Clearance

But he said that the government would need to control expenses, especially on subsidies such as diesel and fertilizers - mainly non-urea, and expand the tax base to generate more revenue to be able to meet fiscal objectives over the long run.

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Also, to comply with prevailing U.S. emissions standards on nitrogen oxides, or NOx, these big diesels require fairly complicated systems of postcombustion treatment with a water-based urea solution, called AdBlue.

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