Sometimes it doesn't take much to improve fuel economy. As part of the run-up to the launch of its Chevy Cruze in the United States, GM is highlighting some of its features. One is a piece of pretty unimpressive technology. It's not an advanced battery chemistries or radical engine design, just a set of shutters that open and close depending on temperature and vehicle speed. (GM is calling this "shape changing" although the changes happen behind a grill and can't be seen easily.) At high speeds, the flaps close to reduce drag. At low speeds or high temperatures, they open to improve cooling of the engine. But, although the tech isn't impressive, the result is significant--an added half mile per gallon.

The flaps couldn't have cost much to add, and they probably could have been included with GM cars years or decades ago. No doubt, provided the right motivation, GM could incorporate other simple measures across its fleet that could improve fuel economy.