Steelhead composites: accumulators/steelheadcomposites.com/golden.

When 9th Street Investments helped finance Loveland's Lightning Hybrids, there was only one supplier making the requisite hydraulic accumulators that recycled brake power into the engine.

"We decided it was a supply chain risk," says Andrew Coors, who subsequently left 9th Street to take the reins of the resulting spinoff Steelhead Composites as CEO and its first employee.

"It stores a tremendous amount of power and almost instantaneously re-applies that to the engine" says Coors. "A hydraulic system is almost instant power."

Unlike less efficient hybrid systems that charge electric batteries - which only capture about a quarter of the braking power - accumulators can recycle 75 percent of the energy and make a vehicle 40 percent more fuel-efficient. Major car manufacturers have taken notice; still, you won't see a consumer vehicle with a hydraulic accumulator until about 2016. "We're very encouraged," says...