Future approaches for reducing motor vehicle emissions and fuel consumption

This paper considers methods of reducing emissions and fuel consumption by changes to both vehicle design and use. Increasing pressure to simultaneously reduce vehicle fuel consumption and exhaust emissions will inevitably lead to a closer optimisation of vehicle operating parameters to the driving cycles used by government authorities for emissions and fuel consumption measurement. This approach is epitomised in the engine mapping concept which is already well established overseas. The paper describes the engine mapping concept for determination of engine spark and fuel requirements to achieve mandatory emission rates and minimum fuel consumption. It is important that vehicles designed using this approach yield similar reductions in emissions and fuel consumption in the real world. An experimental study of driving cycles reported in the paper examined this correlation. This study determined that NOx and HC emissions can be reasonably well quantified by a simple expression of average speed and positive work per unit distance, while CO emissions can be well quantified by average speed alone. The study also demonstrates that, suitably normalised, the equations will predict emissions and fuel consumption for any vehicle or fleet of vehicles (a).