In about two months 24 new "clean diesel" city buses will begin replacing bulkier gas guzzlers now on the streets.

The city and Oahu Transit Services Inc. announced yesterday the purchase of the buses at a cost of $435,696 each, or about $10.5 million total.

Oahu Transit’s president and general manager, Roger Morton, said one of the first things a passenger will notice is how much quieter it is inside.

The new buses use a quieter air-conditioning system that is also more fuel-efficient, Morton said. "That means we should be able to squeeze a few more miles per gallon for fuel, but it also means for our customers you’ll be able to hear our announcements because it won’t be (as much) air that’s moving around the bus," he said.

The buses were built by Canada-based Nova Bus, part of the Volvo Bus Corp. This is the first time the city has contracted Nova Bus to build its vehicles.

"We build buses but more importantly, we build partnerships," said Gilles Dion, Nova Bus president and chief executive officer.

The city said it will continue to use hybrid diesel-electric buses in urban, congested routes, which would yield better fuel economy.

The new buses will be used on less congested, long-haul routes in areas such as the North Shore and Leeward Oahu, where they will be more efficient, Morton said.

Each 40-foot bus can carry 39 seated and 31 standing passengers. They are equipped to carry two wheelchair or scooter passengers and three bicycles. The buses also feature wider front doors and larger windows with lower sills.

The buses are made of a high percentage of noncorrosive materials, including stainless-steel structures, fiberglass bodies and composite flooring, which would extend the life of the vehicles. Each bus will have an electronic sign that flashes a shaka, along with its route number, to drivers behind it.

Morton said the new buses will replace those that are about 17 years old. The older buses will eventually be sold for scrap.