This is the fourth hybrid bus with a power pack designed and built by Traction Technology (UK) Ltd. This particular vehicle is fitted with supercapacitors - devices which absorb and give out electrical energy millions of times without the life issues characteristic of batteries. Electricity is generated as the vehicle brakes. This is stored in the capacitors and released during acceleration. The conventional braking system suffers less wear as a result. The vehicle is returning a 28% improvement in fuel economy with the consequential reduction in carbon dioxide emission.