The increased scrutiny of diesel engines could delay the launch of the diesel-powered Chevrolet Colorado and GMC Canyon.

The increased scrutiny of diesel engines could delay the launch of the diesel-powered Chevrolet Colorado and GMC Canyon.

According to Automotive News, the Environmental Protection Agency (EPA) and the California Air Resources Board have informed General Motors the models won't be certified until they complete a more thorough testing process that includes a road test.

Despite the additional testing, GM remains confident the trucks will pass as Chevrolet Trucks assistant chief engineer Scott Yackley noted the models have already been subjected to on-road and laboratory tests during their development.

As a refresher, the trucks will feature a 2.8-liter Duramax turbodiesel engine that develops 181 bhp (135 kW) and 369 lb-ft (500 Nm) of torque.

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