Noise Assessment of Bioethanol Fuelled Hybrid and Electric Postal Vehicles Equipped With a Kinetic Energy Recovery System

In order to assess the contribution of sustainable mobility to improve environmental conditions in urban areas, new generation hybrid and electric models of mail delivery vehicles are analysed in terms of their noise emissions. Both vehicles use a 10% bioethanol and 90% gasoline mixture (E10) for recharging their batteries and they are equipped with a kinetic energy recovery system (KERS). The difference is the recharge modality: the hybrid vehicle is equipped on board with an E10 fuelled engine for the recharge of its electric batteries while the electric vehicle may be recharged by an E10 engine installed on a specific station (engine is not on board). The aims of the present paper are to carry out objective noise measurements representing realistic urban driving conditions and to compare the noise emissions of the tested vehicles with the ones of traditional postal vehicles. Vehicle sound pressure levels are evaluated according to the international standard ISO 362-1 and the UN/ECE Regulation n. 51 and they reflect a representative combination of all major noise sources. SEL measurements are also analysed as an alternative assessment of noise due to accelerating postal vehicles in actual traffic conditions. Finally all results are compared and their contribution to optimize vehicle noise emission is analysed.