General Motors Corp is to supply diesel-electric hybrid engines for use in a new fleet of buses to be used in California's Yosemite National Park.

The move is aimed at lowering emissions in the pristine nature reserve - the buses boast up to 60 per cent greater fuel economy and 90 per cent cleaner emissions compared to regular diesel buses.

According to Associated Press, it is planned that 18 of the fuel efficient buses will go into service in the park in May 2005.

Mike Tollesfson, Yosemite's superintendent, explained that diesel-electric hybrid's were chosen due to "a significant improvement in fuel economy, dramatically reduced emissions and noticeably quieter operations".

GM's advanced hybrid technology is already being used across America, with more than a dozen major cities piloting the buses.