After Three Month Delay, Diesel GM Trucks Start Production

After a three month delay as a result of the government’s emissions certification, GM has finally begun shipping full-size trucks powered by Duramax diesel engines says Automotive News. Though originally advertised as 2019 models, GM has decided to make them all as 2020s instead.

2020s, Not 2019s

The 2019 gas-powered trucks began arriving at dealers’ lots in August 2018. “Emissions certification took longer than we expected so rather than launching them for one month as 2019s we decided to launch them as 2020 models,” says GM spokesperson Monte Doran.

Because of the Volkswagen “dieselgate” debacle, the feds have gotten more stringent with emissions testing and certification causing longer timeframes. Fiat, Chrysler, and BMW have also seen delays in launching new diesel cars and trucks due to the lengthy certification procedures.

2019 GMC Sierra Denali

The GM diesel gets the best highway mileage of all light pickups with 33 mpg, beating out the Ford F150 turbo diesel at 30 mpg, and the 2018 Ram Classic EcoDiesel at 27 mph. The new 2019 Ram EcoDiesel has not had its numbers made public yet. The last time GM offered a diesel in a 1500 Chevy or GMC pickup truck was in 1997. 


Dieselgate originally stemmed from VW configuring their emissions equipment to recognize when testing was being conducted, immediately activating controls. This caused turbocharged direct injection Volkswagen diesel engines to pass testing. The cheat affected 11 million 2009-2015 vehicles worldwide.

When the California Air Resources Board saw large discrepancies between their tests and data from other sources indicating greater releases of nitrogen oxide, or NOx emissions during normal driving, they decided to study the problem. Once their findings were made public, other agencies around the world conducted testing, finding similar results. 

Of course, the emissions cheat was incorporated into controls because the US emissions tests were too tight to pass, according to numerous experts. 

Many other manufacturers were in on the cheat which included Mercedes, VW, BMW, Audi, Porsche, FCA (Fiat/Chrysler) and more. VW CEO Martin Winterkorn resigned, and heads of development for Audi, VW, and Porsche were all suspended. 

Many Investigations Pending

Many investigations are still ongoing as large discrepancies have been discovered in diesel vehicles manufactured by Citroen, Fiat, Hyundai, Jeep, Renault, and Volvo. 

Diesel engines in trucks are common and popular because they get better mileage than gasoline-powered vehicles, generate more torque for pulling trailers because of the hotter burn rate with the resultant improved efficiency, and last longer between major maintenance needs to be performed.

Light-Duty Diesel Trucks

But diesel engines used in light-duty trucks are a more recent development. They help maintain a company’s average certified economy figures because of better mileage, but they also work more efficiently as trucks continue to increase in weight. As NOx emissions see more restrictive controls for air pollution, it is going to get harder for companies to use these engines in light-duty applications. 

Another factor that may end light-duty diesel trucks are the use of aluminum for both sheet metal and also frame members, making trucks weigh less; and the introduction of electric engines, which companies are scrambling to offer. And in the short term gasoline engines are getting more efficient, too.