Active aerodynamics have long ago filtered down from track cars to high-end sports cars, and are beginning to show up in everyday sedans. But General Motors has patented an idea to use shape-shifting materials to make them more efficient.
More modern cars will soon have active aerodynamic bits — like the shutters in the lower front grille of the Chevrolet Cruze that close at highway speeds, reducing drag and boosting the Cruze's highway fuel economy by a mile per gallon. The Ford Focus will have a similar set-up, and they're expected to become widespread within a few years.
The drawback is the added weight and complexity of whatever powers the shutters open and closed. Electrical motors tend to be among the densest parts on a vehicle, and with higher efficiency standards looming around the world, engineers are always seeking ways to remove weight. (There's also the unanswered question of how well the shutters will stand up to a few tough winters).
The GM patent shows how future systems could use a hinge made from shape-memory alloy — metals that "remember" a shape when heated or cooled, and used already from eyeglasses to jet engines. Instead of having a separate power source, the hinge could simply be heated with a small electric charge, bending whatever active aerodynamic unit into place. (The patent also shows someone at GM likes the Subaru WRX).
The patent doesn't suggest GM would build the entire aero surface from such materials. But how cool would it be to see a Corvette literally grow wings?