Citroen C3 Stop&Start

It's a question Citroen's engineers asked themselves, too. And spurred on by experimental machines such as the 90mpg VW Lupo 3 litre (which debuted stop-and-start technology), the firm built the new C3 Stop&Start. But does it really work? In theory, the underlying principle is very simple. Engineers have done away with the starter motor al-together, using the alternator - which normally charges up the battery - to turn over the engine.

When you pull to a stop, the motor cuts out until you take your foot off the brake pedal. Restarting takes a mere 0.4 seconds and it is very quiet and refined, but the system does mean that your brake lights will be on all of the time that the powerplant is off - which could be annoying for the driver sitting behind. Also, while there are clearly emissions benefits, a mere 5.5 per cent reduction in combined fuel consumption is a little disappointing. City motorists are likely to save more.

The Stop&Start system will only be available on the 1.4-litre 16-valve 90bhp C3 equipped with Citroen's clutchless manual SensoDrive gearbox. Exact costs are yet to be finalised, but company insiders are hinting at a premium of only around ΂£200 for Stop&Start models.