The mtu Hybrid PowerPack is an environmentally friendly drive system which combines the advantages of diesel and battery-powered rail traction. It is a cost-effective, climate-friendly alternative to conventional drives, e. g. for routes that cannot be electrified at all or only partially. The version for Porterbrook, the UK’s largest owner of passenger rolling stock who provides the vehicle to Chiltern Railways, incorporates an mtu diesel engine which will fulfil EU Stage V emissions regulations, plus an electric machine, which can be used either as an electric motor or generator, and an mtu EnergyPack battery system, which stores the energy recovered during braking. This enables very low-noise, emissions-free battery-only electric operation in urban areas and around stations.