As we head into summer vacation season, it's worth noting that hybrids are being used in a somewhat unexpected place - California's Yosemite National Park.

Visitors now enjoy being hauled through the park's 760,000 acres in the Sierra Nevada mountain chain aboard new low-emission, fuel-friendly vehicles powered by Eaton's hybrid electric systems.

Eaton worked with the U.S. General Services Administration and Delaware North Companies Parks and Resorts, which handles the majority of the park's transportation needs, in delivering four new Class 8 tractors with the Eaton diesel/electric hybrid systems to pull the visitor trams. An additional seven vehicles - 37-passenger shuttle buses - are on order and awaiting delivery.

The low-speed, low-mileage and stop-and-go duty cycles at Yosemite provide the perfect operating conditions for a hybrid truck, says Eaton's Kevin Snow, chief engineer for hybrid applications.

Dan Anthonijsz, village garage manager at Yosemite, reports serious fuel-consumption reductions - now averaging about 6.7 mpg with the hybrid tram tractors compared to just 1 mpg with the propane-fueled trucks the new vehicles replaced.

Eaton has published a case study on the Yosemite project - publication number TRSL2517 - that's available for download here.