For the new Saf-T-Liner® C2 school bus, Thomas Built plans to utilize the Cummins Westport ISB6.7 G, a mid-range 6.7 liter natural gas engine, currently in development and expected to be available in 2015.
Thomas Built launched its Type D rear-engine Saf-T-Liner HDX school bus with natural gas in 1992. Since then, the company has put more than 1,300 units of these NGVs on the road and has seen demand increase in the last five years. The HDX CNG bus releases up to 20 percent fewer greenhouse gas emissions than diesel engines.
The ISB6.7 G will be based on the Cummins ISB6.7 diesel engine and will be designed to meet Environmental Protection Agency (EPA) and California Air Resources Board (CARB) regulations in force when it is launched.
Source: Thomas Built Buses