Citroen C3

You may not know that when driving in major cities like Paris or London, more than a third of your journey time can be spent at a standstill. But then again, you probably did know. And while the stats don't apply to motorway journeys, they feel like they do.

Anyway, for all the time you're sitting there, your engine is idling away, spewing fumes into the air vents of the car behind and wasting fuel. Pretty daft, eh?

Citroen thought so and responded with the C3 Stop & Start SensoDrive, which stops the engine every time the car comes to a halt.

When the car slows below 4mph, a light comes on telling you the clutch has been opened, and the engine stops. When you release the brake pedal, the engine starts in a mere 400 milliseconds; accelerate and the car goes. Basically, you drive just as you normally would. The stop-start trick is performed by a starter-alternator connected to the engine by a heavy-duty belt and beefier battery.

The SensoDrive part refers to Citroen's paddle-shifting automated manual gearbox. The car has two-pedal operation like a standard auto, so driving is a cinch.

It will arrives around November and Citroen reckons you can save six to 17 per cent on fuel bills, depending on how heavy the traffic is. So you'll almost be looking forward to city gridlock.

JC

C3 1.4i SX Stop & Start
12/20

We say: Innovative and unobtrusive, will save you cash in heavy traffic and will help cut pollution too

Price: £11,450 (est)

On your drive for: £300pcm (est)

Performance: 0-62mph in 13secs, max speed 112mph, 50mpg

Tech: 1360cc 16v 4-cyl, FWD, 90bhp, 98lb ft, 1044kg, 135g/km CO2