General Motors makes some of the best V6 engines in the world. They also make some pretty average ones that are low cost. Unfortunately for the buying public, GM has a habit of introducing new models with an affordable engine that is sufficient, but not spectacular. It then allows the model to sell to the folks who have been awaiting the new model before re-introducing the vehicle with a more powerful engine on a slightly higher trim level.
The most recent case of this playing out was in the Cadillac SRX. The Cadillac was moved from a body-on-frame design to a crossover unibody platform to better compete with its rival the Lexus RX350. The change was a good one and the vehicle was finally in the right shape to compete in the category. However, to meet a price point and fuel economy target the Cadillac started out with the GM 3.0 liter V6. Critics panned the choice of engine. It did not measure up to the power and refinement of the Lexus and was noticeably slower. Then voilà, Cadillac changed the engine offerings and now the 3.6 liter V6 is the only engine offered. Since the 3.6 liter engine was available all the time the car was being produced, and even used in other Cadillacs, cost and fuel economy could only have been the cause of the 3.0 being used at first. That might cut it in an entry level economy vehicle, but Cadillac stands for so much more.
Now GMC has announced that the Terrain Denali will be offered with the upgraded motor. The larger motor is actually equal to the 3.0 liter engine in terms of fuel efficiency now and of course has more torque and power. To keep weight down the new engine uses lightweight materials and also combines parts into one structure where possible. For example, rather than having separate cylinder heads and exhaust manifolds, the new engine integrates these two parts saving over 5 pounds. There are also likely cost savings for the parts as well as possible installation time savings.
To the delight of customers, GMC has upgraded the old engine to the high content 3.6 liter V6, a move that worked well in other crossovers in the GM family.