Ford's new Focus Econetic will be the company's first model to feature stop-start technology when it goes on sale in 2010, bringing CO2 emissions down to just 99g/km.
Known as Auto-Start-Stop, the system switches off the engine when the vehicle is idle, such as at traffic lights, and restarts it again in 0.3 seconds when the driver wants to move off, saving the fuel that would have been wasted while the car was stationary.
Other eco technologies on the Focus Econetic include regenerative charging harnessing braking energy to recharge the battery and Eco Mode, a system that helps educate the driver to drive more efficiently.
The 1.6-litre TDCi engine emits just 99g/km in models with Auto-Start-Stop. Longer gear ratios also help reduce engine revs and noise, and average fuel consumption will be 74.2mpg.
Greener driving isn't just a case of technical improvements to the car; much is down to the driver, too. So Ford's Eco Mode system monitors your driving style from when you change gear to how smoothly you drive and the efficiency of your speed on the motorway.
A driver profile is generated, with advice on how to improve your fuel economy over time.
Five-door and estate versions of the Focus Econetic will be available without Auto-Stop-Start, but emissions will rise to 104g/km, while fuel economy will drop to 70.6mpg.