This is from the Metro Transit-CITY OF MADISON website. They have received hybrids in 2007.
- Allison Electric Drive System
Metro's new hybrid buses are powered by the Allison Electric Drive system, which reduces exhaust emissions up to 90% compared to conventional combustion engines.
Up to a 60% improvement in fuel economy has been demonstrated in a vehicle with an Allison Electric Drive.
Play Video (GM Advanced Hybrid Technologies)
- Regenerative Braking
Forty percent of the energy to accelerate the bus is energy saved during regenerative braking. When stopping or decelerating, vehicle energy is converted to electric energy and stored. In effect, the motor becomes a generator.
An Allison Hybrid Electric Drive System can significantly out-accelerate a vehicle equipped with a conventional drivetrain or an alternative fuel system.
Play Video (Regeneratrive Braking and the ESS Smart Design
- Allison Electric Drive System - EP System Familiarization
As explained by Bill Nye the Science Guy!
Learn more about the EP System, a parallel hybrid that blends both mechanical and electrical power paths to drive a vehicle.
By using a smaller internal combustion engine, and operating it only in its most efficient ranges, the EP System reduces fuel consumption and emissions and increases productivity and passenger comfort.
• Play Video (EP System Familiarization....Featuring Bill Nye the Science Guy)