Reader Question: Passing Smog Check With an Older Diesel?

Here’s the latest reader question, along with my reply!

StuckInSoCal asks: I follow a YouTube channel that seems to provide good advice, for cost effective Mercedes-Benz sedans (rare and interesting). I’m thinking about a pre-DEF diesel car. He thinks that an E320 CDI might be a good choice; made in ’05-’06 only, pre-DEF, shares all parts with the ubiquitous E Series of the time, uses durable 5 speed auto available fleet-wide until 2004, mileage rating great, etc.

Question is smog check. Metro NV or CA are my choices for registration, both require diesel smog testing. Any details about what is required to pass? Used the Internet, but got no detail about exact details of what constitutes a fail in either state (emissions levels, etc.)

My reply: This one’s easy!

First, these are great cars – hugely recommend, for all the reasons you’ve adduced. Diesels like they used to make ’em, durable, efficient and very long-legged/long-lived. Mercedes historically made among the best diesel-powered vehicles you could buy, period. So a full anointing and amen on the E320.

Second, smog check should be a non issue in either state assuming the car is stock – not modified – and in proper tune. The laws only require that a given car – whether gas or diesel – comply with whatever standard was applicable at the time of manufacture. Put another way, an ’05-’06 E320 will pass smog check so long as its emissions are in spec for those model years; it does not have to comply with current standards.

Yet.

One caveat: Te above assumes the car was originally legal for sale in CA or NV. It is possible you could have an issue if the car was “49 state” but not “California” when it was new.

Other than that, you should be fine!

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