The phenomenon, known as 'Turbo-lag', is most noticeable when a sudden load change is applied at lower engine speeds combined with rapid acceleration. Turbocharged vehicles are commonly used but they exhibit a weak point of poor performance under transient running conditions. A method of reducing the emissions of an internal combustion (IC) engine is to use smaller engines but recover power lost due to reduction in size by using a turbocharger or supercharger. Growing global concern pertaining to climate change has meant that engine development has become more focused on engine emissions.