The Whatcom Transportation Authority put eight new hybrid diesel-electric buses into service on Monday, Feb. 4.

Although the price tag on each bus was higher - $594,000 for a 2012 hybrid, compared to $394,000 for a comparable 2012 diesel - the hybrids run cleaner, are more fuel efficient and cost less to maintain, according to WTA.

The new buses, recognizable by their distinct green and blue exterior design, are 40 percent more fuel efficient than the 18-year-old diesel buses they replace, a WTA statement said.

Lettering on the exterior of the buses also touts "near-zero emission." In addition to reduced diesel exhaust when the battery is in use, the buses have two emissions controls: a filter that traps soot and unburned hydrocarbons, and a device that reduces nitrogen oxides, which contribute to smog.

The buses taken out of service averaged 575,000 miles on the odometer. The replacements, made by Gillig out of Hayward, Calif., will save the transit agency about $100,000 a year in maintenance and fuel costs.

The Federal Transit Administration awarded WTA two grants totaling $4.4 million to purchase the buses. This covered 83 percent of the total cost; the rest came from WTA's fleet replacement budget.

Much like hybrid passenger cars, the batteries in the buses recharge when the brakes are applied. Hybrids like this typically get better fuel efficiency during urban driving. WTA plans to use the buses on routes within Bellingham and on some longer routes, such as Sudden Valley and Ferndale, WTA spokeswoman Maureen McCarthy said. The buses will not be used on the 80X to Mount Vernon.

WTA wants to assess whether the hybrids get satisfactory mileage on the longer routes, McCarthy said. If not, the buses could be moved to urban-only routes.

"We were originally told the buses would be most efficient on urban routes," McCarthy said. "We wanted to test that out."

Community Transit in Snohomish County put its first hybrids into service on a long-distance route between Everett and Shoreline in 2009.

The eight WTA hybrids complete the agency's recent project to replace 28 buses in its fixed-route fleet of 57 buses. If the hybrids meet expectations, WTA is likely to purchase similar buses in the next round of replacements, McCarthy said.

The percentage of bus cost paid for by federal grants was corrected Feb. 6, 2013.

Reach Ralph Schwartz at 360-715-2289 or ralph.schwartz@bellinghamherald.com. Read his politics blog at blogs.bellinghamherald.com/politics or follow him on Twitter at @bhamheraldpolitics.