GM delays diesel-powered Chevrolet Silverado 1500, GMC Sierra 1500 until 2020

The EPA is taking longer than usual to certify the trucks.

General Motors has postponed the launch of the new straight-six turbodiesel engine it developed to power the Chevrolet Silverado and the GMC Sierra. The firm expected to make the engine available for the 2019 model year, but buyers will now have to wait until the 2020 models begin arriving in showrooms.

The engine is ready, its development process has ended, but obtaining an emissions certification from the Environmental Protection Agency (EPA) is taking longer than expected, according to Automotive News. The publication obtained a memo sent to dealers which explains the situation will cause a "slight delay" in deliveries. However, dealers who ordered a diesel-powered truck will need to cancel their order and re-submit it when the engine is certified by the EPA.

There's no word yet on when production of the diesel-powered Silverado and Sierra will begin; a GM spokesperson told Automotive News that manufacturing will begin "soon" without providing a more specific time frame. The EPA hasn't commented on the delay, or on the certification process.

The 3.0-liter Duramax engine will be available in the 1500 variants of the Silverado and the Sierra. It will deliver 277 horsepower and 460 pound-feet of torque, and it will be bolted to a 10-speed automatic transmission. Fuel economy and towing figures haven't been released yet.

Until production begins, truck shoppers who want a diesel without stepping up to a heavy-duty model will need to shop at Ford. The F-150 is offered with a 3.0-liter turbodiesel V6 rated at 250 horsepower and 440 pound-feet of torque. Rival Ram plans to add a turbodiesel V6 to the 1500 line-up, but it hasn't announced specifications, and the engine likely won't arrive until the 2020 model year.