COLLINS, CO – In 2003, FedEx bet on hybrids, predicting the vehicles had the potential to replace the company's 30,000 medium-duty trucks over the next 10 years. The company isn't quite there yet. Currently, it only has 172 of the trucks on the road, according to Fast Company.

Mitch Jackson, FedEx's director of environmental affairs and sustainability, believes the main problem is that not enough companies have joined FedEx in testing hybrids. Because other companies have not ordered test vehicles, prices remain high. The hybrid engines Eaton Corp. produces for FedEx carry a 75-percent price premium.

The company also bet that federal incentives would help defray the high costs. That hasn't happened. The 2005 energy bill included provisions for commercial-hybrid-truck-tax credits, but they were never put into place by the IRS. Large companies like Coca-Cola and AT&T are now bringing hybrid trucks into their fleets. This may eventually push engine prices down.