LOS ANGELES --- General Motors' Chevrolet made a splash at the Los Angeles Auto Show when it introduced hybrid versions of the Silverado and Tahoe featuring GM's advanced two-mode hybrid transmission system. The two-mode hybrid system was developed in partnership with Daimler, Chrysler and BMW. It is designed to power big vehicles with major towing and cargo-hauling capabilities. The two-wheel-drive hybrid Tahoe offers 21-mpg city mileage and 22-mpg highway mileage. That achievement earned it the Green Car of the Year award, given out by the Green Car Journal. The first mode of GM's two-mode hybrid system works at lower speeds, while the second mode is used on the freeway or while towing. The second mode has its own battery, motor and gears.