The cleaner Citroen

We've had the high mileage diesel, the petrol-electric hybrid and the 100% electric. Now meet the Stop & Start, Citroen's ingeniously clever engine that switches off when you brake to a halt and automatically reignites in milliseconds when you put your foot on the accelerator. Though the tech was announced last September, it's only been available in the UK for a few months in the cute C3, pictured. Citroen reckon it reduces fuel and CO2 emisssions by up to 15% if you battle through daily traffic jams. I'm aiming to give one a test-drive; Autocar say it's good but a bit cramped in the rear seats.