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.

GM has announced that it will sell the much-anticipated Chevrolet Volt--an electric car with a gas generator for extending driving range--for $41,000, which is about what people had been expecting. The automaker notes that with a federal tax credit, the actual cost to consumers is $33,500.

GM starts taking orders for the car today. It will be available initially in California, New York, Michigan, Connecticut, Texas, New Jersey and the Washington D.C. area. To buy one, you need to go to a Volt dealer, which you can find at http://www.getmyvolt.com.

The car costs more than the Nissan Leaf, which is also coming out this year. That car will sell for $32,780, or $25,280 after the tax rebate. Both are far more expensive than GMs new, more fuel efficient sedan called the Cruze, which costs $16,995 and is similar in size to the Volt.

With the Cruze, you can get 40 miles per gallon (with the Eco version). The Volt offers 40 miles of electric range with a charge, and 300-miles more with a range-extending gas generator. The Leaf offers 100 miles of gas-free driving range between charges.