HARTline unveiled three new General Motors hybrid-powered transit buses Friday. The buses, which have better fuel economy and cleaner emissions than diesel buses, were taken for a test drive with GM and HARTline officials and local media in the passenger seats. The buses accelerate by way of an electric motor and regenerate power by braking. The buses also have a traditional diesel engine. Each bus costs $490,000, but HARTLine anticipates saving money on operating costs for each bus. Two of the buses went into service Friday.