The Toronto Star reports that the Toronto Transit Commission (TTC) is about to spend up to $110 million on 100–150 hybrid electric buses—one of the largest single hybrid bus purchases in North America.

The inside favorite for the business appears to be Mississauga-based Orion Bus Industries, a division of DaimlerChrysler.

New York City, which operates North America’s largest bus fleet, has 125 Orion hybrid buses already in service with 200 more being built. Seattle has the largest in-service hybrid fleet in the world, with 210 buses manufactured by Winnipeg-based New Flyer.

Unlike the New Flyer buses, which use the GM-Allison parallel hybrid drive, the Orion VII buses are series hybrids, using a propulsion system from BAE Systems.

The Orion VII buses with the BAE HybriDrive combine a 5.9-liter, 260 hp (194 kW) Cummins ULSD (Ultra Low-Sulfur Diesel) engine with a 120 kW traction generator. The traction motor delivers 250 hp (186 kW) and 2,700 lb-ft (3,657 Nm) of low-end torque.

New York City transit reports average gains in fuel efficiency of 28% over conventional diesel buses. Emissions reductions are substantial. (Click to enlarge.)

Should TTC purchase the hybrids, the new vehicles would represent 7–10% of the 1,500 bus fleet. TTC has already introduced ultra low-sulfur fuel, and began using biodiesel in 180 of its buses as well.