Paying an extra $200,000 to boost your vehicle's fuel economy by 1 mile per gallon isn't something you'd probably want to do -- unless you're a transit agency pledging to "go greener."

Metro Transit showed off 17 of its newly acquired hybrid buses Thursday on Nicollet Mall, and it was perhaps the quietest, cleanest parade of buses the Twin Cities has ever seen.

The hybrids cost $557,000 each, and the ones already in Metro Transit's fleet have averaged 4.71 miles to the gallon, compared with 3.86 for a standard bus. A one-mile-per-gallon difference might not seem worth the fuss, but in percentage terms, it's significant.

Metro Transit is expecting a 22 percent or greater improvement in fuel economy, which translates to 1,965 gallons of fuel per bus saved annually, along with less soot and other pollutants.

Theresa Cooke, who commutes from northeast Minneapolis to downtown, has already ridden on a hybrid. Her bus, the 17, has been serving as a test route, and she had good things to say Thursday.

"Inside the bus, it was really quiet," she said, noting that she appreciates being in a bus with a newer interior. She also praised the hybrids, which have a low-floor design, as being "a lot more handicap accessible."

The federal government pays 80 percent of the cost of a new bus, with local sources paying the rest. Once all 172 hybrids in the total fleet of more than 800 buses are running in five years, Metro Transit is expecting to save 338,000 gallons of fuel a year.

Bob Gibbons says that the lower operating expenses mean that Metro Transit can recoup the local portion of the extra cost per bus in a little over six years. He based that on the current fuel price of $3.25 a gallon. If the price rises, the state gets its investment back sooner, he said.

Metro Transit has been using three hybrid buses since 2002, and they were more or less alone until 19 more arrived in the past few weeks. To tempt more people to give them a try, the agency announced that rides on the hybrids -- which are wrapped in green "Go Greener" advertising -- will be free on Monday on routes 17 and 18. Those routes both go down Nicollet Mall, where shoppers and diners are expected to benefit from the reduction in noise and exhaust.

Starting Tuesday and running through the end of the year, a hybrid bus will make the rounds of other routes in the system and offer free rides.

Why now?

Gibbons said more hybrids would have arrived sooner if money had been available.

"We went through a period of two or three years when we didn't buy any buses because we didn't have the funding to do so," he said.

The Metropolitan Council, which oversees Metro Transit, has authorized the agency to purchase 310 buses over the next four years, and 150 of those will be hybrids.

The agency chose hybrids over buses run by another environmentally friendly technology, compressed natural gas, because Metro Transit would have had to set up costly refueling stations.

Like the rest of Metro Transit's fleet, the hybrids will run on fuel that is 10 percent biodiesel in the winter and 20 percent in the summer. The biodiesel, which is made in Brewster, Minn., and blended with regular diesel in the Twin Cities, tends to get gelatinous at cold temperatures.

More in Seattle

Jim Boon, who is in charge of bus maintenance for the Seattle area, doesn't much worry about such things -- it rarely gets cold enough in his city for the biodiesel to run thick. His agency, King County Metro Transit, had 236 hybrid buses on the road by the end of 2005, all of them the longer, articulated buses.