Start-stop no-go for local auto Audis

Audi will introduce start-stop versions of its dual-clutch S tronic A3 1.6 TDI and 1.4 TFSI in Europe during November. The technology will come to Australia on unspecified Audi models next year, but -- for the moment -- only in manual transmission form.

The new start-stop system just announced by Audi for its A3 1.6 TDI and 1.4 signals the first-time application of the technology to Audi's S tronic dual-clutch transmission.

Audi start-stop has been available in manual transmission models -- on certain markets only -- for some time, but S tronic drivers have so far been denied the fuel consumption and emission-friendly technology.

Despite its seemingly simple modus operandi -- the engine stops when the car is stationary, starts again when required -- the delay has apparently been caused by technical difficulties.

But the benefits justify the wait. In addition to sitting quietly in stationary traffic, the start-stop S tronic Audis are super-clean and thrifty when measured for emissions and fuel consumption.

The diesel 1.6 TDI A3 with start-stop consumes fuel at the rate of 4.2L/100km, while approaching the 100g/km barrier with CO2 emissions of just 109g/km. The petrol 1.4 TFSI consumes 5.3L/100km of premium unleaded and emits 124g/km of CO2. The regular A3 1.4 TFSI Sportback produces 137g/km.

If there's any downside, it's the acceleration -- of the TDI at least. While not exactly slow, the 77kW/250Nm diesel's zero to 100km/h figure of 11.7 seconds isn't exactly fast. The 92kW/200Nm petrol TFSI is quite a bit better with a zero to 100km/h time of 9.3 seconds -- 0.2 of a second faster than the regular S tronic version.

There's a bit more than start-stop to the new S tronic combinations too: both use an "on-board energy-recovery system" in which the alternator charges the battery during braking or engine over-run, then feeds it back during acceleration to save fuel by reducing the electrical load.

The start-stop A3 S tronic Audis will be available in three-door and Sportback form in Germany from November this year -- but won't come to Australia.

Word is that hot-climate difficulties preclude local introduction of the technology at this stage -- but there is an upside. Audi will be bringing start-stop here in some manual transmission vehicles in 2010, although it is not saying which models as yet.

With Audi joining a growing list of start-stop equipped vehicles, it won't be long before city traffic turns eerily silent.

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