Volvo's C30 1.6D DRIVe with stop/start has been named Green Car of the Year by the website The Swedish manufacturer's most economical model achieves an impressive 74.3mpg on the official combined cycle fuel consumption tests and emits just 99g/km of CO2, making it one of only a small number of cars to break the 100g/km barrier.

The C30 DRIVe's fuel consumption and CO2 performance are very similar to those delivered by the stop/start Ford Focus ECOnetic that we featured recently. That's hardly a surprise given that, under the skin, Volvo's smaller models – the C30 coupe, S40 saloon and V50 estate - are sister models of the Focus, although these model families may in future diverge if Ford succeeds in its present plan to sell Volvo.

Stop/start systems are an increasingly popular fuel-saving feature on today's cars. Some manufacturers like Ford and Volvo fit them only to their specialised economy models while others use the technology more widely; for example, BMW fits it across the MINI range. Stop-start systems save fuel by automatically shutting down a car's engine when it comes to a rest, and then automatically restarting it when the driver engages gear or presses the accelerator; in most cars fitted with such a system, it works unobtrusively and quickly. Often the technology works in conjunction with features such as improved batteries and regenerative braking, in which case the car concerned is sometimes described as a micro-hybrid.

Volvo produces fuel-saving DRIVe versions of its other cars featuring the same 1.6 litre diesel engine as that found in the C30, including the big S80 DRIVe we tested a few weeks ago – although that one isn't available with stop/start technology so far.

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