Enterprise Holdings, owner and operator of the Enterprise Rent-A-Car, National Car Rental and Alamo Rent A Car brands, says it is planning to fuel additional shuttle buses airport locations with 20% biodiesel (B20).

"We are steadily converting our shuttle fleet as biodiesel becomes accessible to more and more of our airport locations," says Lee Broughton, head of corporate sustainability at Enterprise Holdings.

The company has already converted all of its shuttle buses to biodiesel at airport locations within five miles of a biodiesel fueling station. Overall, more than 70% of its buses now run on biodiesel, with approximately 50% using five percent biodiesel (B5) and more than 20% using B20.

By the end of this year, all of the company's older buses will be replaced with new B20-compatible models, at which time more than 80% of its total shuttle bus fleet will be running on biodiesel.

Enterprise notes that it also operates 30 buses fueled by compressed natural gas in Southern California, and 10 more CNG-fueled buses will come online this year.