Testing is underway at Bob Hope Airport that could spell the end of the facility’s diesel-powered bus fleet. The test involves a bus that is fueled by compressed natural gas. If the test is successful, airport commissioners could decide to convert the rest of its fleet to CNG-power.

The CNG-powered bus, which has been in operation for a month, was shown to Burbank-Glendale-Pasadena Airport Authority commissioners on Monday morning.

“This bus is quieter, more powerful and a much smoother ride,” said Fleet Supervisor Marco Rodriguez. “Customers can tell right away.”

Mark Hardyment, director of Environmental Programs at Bob Hope Airport, said he was relieved to finally announce the shuttle’s regular service.

“This is part of a voluntary effort on behalf of the airport to lower emissions,” Hardyment said.

CNG vehicles were recommended as an alternative fuel option in an earlier environmental study by the airport authority. Depending on its performance, the authority may apply for federal funds to convert the rest of its fleet of 13 diesel buses to CNG-power, Hardyment told commissioners.

After setting aside $700,000, or $50,000 per shuttle, it ended up costing $155,000 to replace the power system of the bus, according to officials. That means the cost to convert the rest of the fleet would be roughly $2 million.

A federal grant would bring the matching funds requirement down to $400,000 to change over the rest of the shuttles, Hardyment said.

Gas prices on Monday hovered around $4 a gallon, but when the bus went in for a morning fill-up — at a pressure of 3,600 pounds per square inch or the equivalent of about 44 gallons — the cost was $2.59 a gallon at the Burbank compressed natural gas fueling station on North Lake Street, said tram supervisor Sarkis Avetic.

A diesel bus holds 70 gallons and is much more expensive to fill up, he added.

The new bus can run two shifts a day for two days before needing to refuel, Hardyment said.

Similar buses in Glendale have been met with praise, said airport commission President Frank Quintero, who serves on the City Council.

“We’ve had tremendous success with [compressed natural gas] vehicles,” Quintero said. “The best response has been from bus drivers who are happy to not smell the [diesel fumes].”

The authority will be tracking the shuttle’s performance over the next few months before deciding whether to file an application for grant money to fund the refurbishment of the entire fleet.