interior floor height is , corresponding to the first step height of the front door ( when knelt) and for the rear step height. To facilitate the full low-floor design, the suspension features an independent front design using MacPherson struts and an inverted rear portal axle. OBI marketed the Orion VI to both the Canadian and United States transit markets. Canadian buses were assembled at the OBI plant in Mississauga, Ontario. For the US market, to meet 'Buy America' requirements for federally subsidized transit vehicles, the Orion VI was partially assembled at Mississauga, then shipped to Oriskany, New York for final assembly by wholly owned subsidiary Bus Industries of America (BIA). Internally, OBI designated the bus model as 06.501. Hybrid A prototype series hybrid bus was developed by the New York State Consortium using an Orion V 40' chassis equipped with powertrain components supplied by General Electric. This hybrid bus prototype used tandem rear axles driven by four traction motors, one for each wheel. Electric traction power was generated by a Cummins B5.9 diesel engine rated at driving a alternator, and energy from regenerative braking was stored in nickel-cadmium batteries. In 1998, the Orion VI became the first North American transit bus to be offered with a hybrid powertrain as a regular production option. The New York City (NYC) Metropolitan Transportation Authority was the lead customer, with an order of 125 Orion VI Hybrid buses planned for delivery in 2002. The series hybrid powertrain, developed from the Orion V prototype by Lockheed Martin and marketed as HybriDrive™, differed in adopting a single rear axle driven by one traction motor, storing energy in lead-acid batteries, and using a Detroit Diesel Series 30 (a co-branded Navistar T444E) V-8 diesel engine turning a generator. A pilot fleet of 10 Orion VI Hybrid buses was sold in 1998 to MTA for $5.6 million. During durability testing at Altoona, Pennsylvania, the roof-mounted battery packs failed shortly after the bus was received, resulting in a prolonged unavailability of more than 1000 hours, and the traction motor failed three times. Deployment The Orion VI was mostly sold in Canada. Major transit agency users included New York City (MTA), Ottawa (OC Transpo) and Toronto (TTC). TTC retired its Orion VI fleet in 2006 after less than ten years of service. The Orion VI for TTC had been purchased with CNG engines, and rather than convert them to diesel