I couldn’t give you specifics other than the HD Cooling KNP option I believe was duel core with transmission cooler. So, I guess GM considered it a better option.Is a single core less efficient than a dual core if the dual core is comprised of two smaller cores? From my understanding, the advent of dual core only reduced the size of each individual core. Fluid dynamics tells me there is a marginal, if any, improvement in heat dissipation between one larger core versus two smaller cores. It the dual core was made with two cores of the same size as the single core then, yes, by all means it would be more efficient.