Light-Duty Diesel Engines Slow to Return to Showrooms in Wake of Emissions Scandal | Edmunds

Light-Duty Diesel Engines Slow to Return to Showrooms in Wake of Emissions Scandal

SANTA MONICA, California — A federal judge may have approved a $14.7 billion court settlement relating to the Volkswagen diesel-emissions cheating scandal, but that doesn't signify that sales of light-duty diesel cars and SUVs are poised to return to pre-crisis levels. 

On the eve of the settlement, Automotive News pointed out that Jaguar is the only brand with 2017 diesel engines certified and ready to sell. A quick check of inventory on confirmed that diesel-powered 2017 Jaguar XE and XF sedans are indeed ready and waiting for buyers.

But that's it.

Audi and Porsche have deep corporate ties to Volkswagen, so it's no surprise that their diesel offerings are in deep limbo. But that doesn't explain the absence of the Ram 1500 EcoDiesel, Jeep Grand Cherokee EcoDiesel or BMW's 3 Series, X3 and X5 diesels. Detailed 2017 pricing has been published, but they are not for sale and diesel fuel economy data is conspicuously absent from

The picture is even murkier for the Range Rover diesel and the Mercedes GLE and E-Class diesels, none of which appear in 2017 order guides. The same is true of the Chevrolet Cruze and the Chevrolet Colorado/GMC Canyon diesels.

The issue swirls around emissions approval. Diesel engines emit much more oxides of nitrogen (NOx) than gasoline ones, and the demanding emissions regulations in the U.S. cut light-duty diesels no slack. A secondary exhaust catalyst and a diesel exhaust fluid (DEF) injection system are necessary to take care of the extra NOx.

Volkswagen decided it could literally drive around the requirement by burying cheat codes in its diesel engine control software. The test patterns used in lab testing are very strictly defined, and that made it possible for someone to craft software that would only turn on the NOx control system when someone dressed in a lab coat was looking.

No one expected such a brazen tactic from a major auto manufacturer, and the EPA knows it can't let this happen again. According to Automotive News, "EPA officials have said little publicly about the enhanced testing, saying only that vehicles would be kept longer and tested in unpredictable ways."

At a minimum, the EPA is running its own dyno tests and subjecting manufacturer-reported results to greater scrutiny. And it's likely officials are strapping Portable Emissions Measuring (PEM) devices to test vehicles and driving them on actual roads to ensure the lab tests match. All of this (and surely more) is slowing down the certification of 2017 light-duty diesel cars, pickups and SUVs.

This seems like a temporary setback, at least technically. But the resilience of customer demand is harder to judge. Light-duty diesels still have a place in the market — particularly the light-pickup and SUV segments that value torque and towing. But those who bought a diesel-powered car for fuel economy alone will likely be tempted by hybrid offerings instead. And since the biggest player may not soon re-enter the segment, it's likely that the peak days of the diesel sedan are behind us.

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