New research has placed BMW at the top of its class for lowest average CO2 emissions. Drivers looking for car insurance for their greener vehicle may be interested in the research carried out by CleanGreenCars, which stated BMWs produce the lowest amount of emissions compared to other premium car manufacturers. A fleet average, based on all BMWs sold last year, came in at 159.4 g/km - which is due to the EfficientDynamics programme, according to the company. The system, which was first offered as standard in 2007, includes Auto Start/Stop, electric power steering, Active Aerodynamics, Brake Energy Regeneration and other features. BMW claims its models equipped with EfficientDynamics - such as the Z4 Coupe and Roadster - have cut CO2 emissions by 58,000 tonnes in the past two years. According to the research, the average CO2 emission recorded for Audi stood at 173 g/km, for Mercedes-Benz it was 189.9 g/km and for Porsche is was 271.7 g/km.