Cadillac is dropping a 400-horsepower twin-turbo V6 in the CT6 ... economy by up to an estimated 6 percent. Cylinder deactivation temporarily deactivates two of the cylinders in light-load ...

The CT6 is Cadillac’s largest sedan, sized and equipped to challenge models like the Audi A8 and Lexus LS. But thanks to copious amounts of advanced engineering it’s up to 1,000 pounds lighter ...