Drivers in pothole-plagued cities, rejoice: Researchers have invented a shock absorber that can partially power a car while smoothing the ride.

When a vehicle using the technology hits a small bump in the road, hydraulic fluid squirts into a turbine. The turbine then spins as fluid runs through it, powering a small electric generator. The system, which could someday help power hybrid cars, is controlled by electronics that ensure a much smoother ride than normal shocks while simultaneously generating electricity for the car to use.

A team of mechanical engineers, led by Shakeel Avadhany at Boston's Levant Power Corporation, designed the system, which they've dubbed GenShock.

Road Test

The U.S. military will be the first to give GenShock a test drive.

Improved fuel efficiency would mean hauling less fuel through war zones. And a smoother ride would make handling safer, allowing soldiers to drive over rough terrain faster.

Levant is developing the regenerative shock absorber for the next-generation Humvee, then for the heavy-truck and consumer-hybrid markets, said Avadhany, an undergraduate at the Massachusetts Institute of Technology.

When installed on a 40-mile-per-gallon hybrid vehicle, the recovered energy can be used for fuel-efficiency gains between 3 percent and 10 percent. This is equivalent to up to a four-mile-per-gallon increase in fuel economy.

"Just as in the case of regenerative braking"-a technique used by some hybrid vehicles to generate electricity from energy released when a car brakes-"one could dump the extra energy in a battery instead of in the atmosphere," said Karl Hedrick, a professor of mechanical engineering at the University of California, Berkeley, who was not involved in the research.

"I don't know how significant this will be, but it sounds good."