A team of MIT undergrads has developed a shock absorber that aborbs the shock of a bump in the road and turns it into usable energy.  Making use of this energy makes the vehicles 10% more fuel efficient. 

The project started as a quest to find where energy is being wasted in vehicles.  Taking note of how some new hybrids recover the energy lost in breaking (regenerative breaking), they turned their attention to the suspension. 

They started their testing by renting a variety of different cars and and outfitting the suspension systems with sensors.  They then drove around town with a laptop monitoring the energy loss.  They found that there was a significant amount of energy lost by the suspension, especially on heavier vehicles. 

Armed with that knowledge, they hit the shop and built a prototype that uses a hydraulic system with a turbine and attached to a generator.  When you go over a bump in the road, the shock is depresses pushing the fluid through the turbine, which is attached to the generator that turns that energy into electricity.  Besides harvesting lost energy, the system actually provides a smoother ride because it is controlled by an active electronic system that optimizes the damping of the shock. 

The energy that is produced can recharge a battery, or be used to power other electric systems like interior of a passenger car, or even a refrigeration unit on a cargo truck. 

Source: MIT via Gizmodo