Chevrolet Introduces Colorado ZR2 Concept Aggressively styled, more capable and driven by new 2.8L Duramax diesel engine LOS ANGELES – Chevrolet today introduced the Colorado ZR2 concept – a vision of how Chevrolet could take the all-new midsize truck’s off-road capability to the next level. It also showcases the new 2.8L Duramax diesel engine that