I graduated high school in 1981, and that same year the beautiful Cadillac Seville with its' monstrous V8 engine was re-engineered for better gas mileage and what they did was brilliant. They kept all eight cylinders so people would have the power they needed when they needed it but it could drop to six and even four cylinders when cruising at lower speeds. A significant achievement that year.
I find it interesting how the best technology is driven by broad-based legitimate needs. I'm not a huge GM fan but I have to give them kudos on this one.