He was talking about new diesel vehicles. Of course completely different rules apply to old ones, and those depend on the state. In urban NV all light-duty vehicles, gas or diesel, that are between 2 and 40 years old must have annual emission checks. But they're pretty hard to fail unless there's something horribly wrong with your car.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL