May 11, 2009 It may sound obvious, but the most effective way to cut a car's fuel consumption is to turn the car off. Of course that isn’t very useful if you're trying to get from A to B. But for many trips, particularly for city driving, a car can be idle for a significant amount of time. Audi has now joined the likes of Citroen and BMW by offering a new system that shuts down the engine when the car comes to a stop. The start-stop system joins a new on-board computer, as part of Audi’s modular efficiency platform, which is designed to reduce fuel consumption and cut carbon emissions.

The start-stop system shuts down the engine once the car has stopped. The gear lever stands at idle and the driver releases the clutch pedal. Then once the clutch pedal is pressed the engine starts up again. Audi claims the system is very quiet and, more importantly, quick, with the engine returning to idle in the time it takes the driver to change gears. Under standard driving conditions, the start-stop system lowers fuel consumption by about 0.2 liters for every 62 miles (100km), which translates to a reduction of CO2 emissions by about 5g a kilometer. The system can also be turned off with the press of a button.

In addition to the start-stop system, Audi has another environmentally friendly initiative: an on-board computer with efficiency program. According to the car maker, up to 30 percent of fuel consumption depends on the individual driving style, so the on-board computer continuously analyzes the energy consumption in the vehicle and gives the driver tips for saving fuel. These driving recommendations are shown on a center display, along with all fuel-consumption data. This includes information about how systems, such as air conditioning and seat heating, are affecting fuel consumption, and whether the correct gear is engaged for optimal fuel economy.

The start-stop system and on-board computer are a part of Audi’s modular efficiency platform, which is designed to improve the entire vehicle’s energy management – be it through new powertrain technologies or more efficient air conditioning. By 2012, Audi hopes to lower fuel consumption of its model range by 20 percent compared to its 2007 models.

Both the new start-stop system and the on-board computer will be available in models from the second quarter of 2009. The start-stop system will be used for the first time in the Audi A3 1.4 TFSI, Audi A4 and A5 with manual transmissions. Numerous other models will follow later in the year.

Darren Quick