Automatic start-stop systems have become increasingly common in Europe in the last few years, but until now they have pretty much only been available on cars with manual transmissions. Audi is looking to change that with the introduction of a new system on the A3 that is paired with the 7-speed S-tronic dual clutch transmission.

The setup is available on two different A3 models, the 105 hp 1.6 TDI diesel and the 125 hp 1.4 TFSI gas engine. In both cases, the cars are also equipped with brake energy regeneration which captures some energy during coast down to charge the battery. This has the effect of reducing the alternator load on the engine during acceleration.

While this is Audi's first such application, it isn't so different from the GM mild hybrid system which was offered for several years on the Saturn Vue and Aura and the Chevy Malibu. The 1.6 TDI gets an EU combined rating of 56 mpg (U.S.) with CO2 emissions of 109 g/km while the 1.4 TFSI is rated at 44.4 mpg (U.S.) and 124 g/km.

[Source: Audi]


World premiere: Audi combines start-stop function with automatic transmission

* Convenience and efficiency combined
* Use in Audi A3 1.6 TDI and 1.4 TFSI
* Innovations from Audi's Modular Efficiency Platform

Thanks to the synergetic impact of technologies from the Modular Efficiency Platform coupled with Audi's technological expertise, the start-stop system is now being offered in conjunction with an automatic transmission. The A3 1.6 TDI with 77 kW (105 hp) and the 1.4 TFSI with 92 kW (125 hp) combine – for the first time – the start-stop function with the innovative S tronic dual-clutch transmission.

The start-stop system turns the engine off as soon as the vehicle comes to a stop; the engine stays off as long as the driver depresses the brake pedal. As soon as the driver removes their foot from the brake pedal, start-stop turns the engine back on – quietly, conveniently and quickly.

In addition to impressive driving performance, these A3 models sip an exemplary 4.2 liters of diesel per 100 kilometers (56.00 US mpg) (1.6 TDI) or just 5.3 liters (44.38 US mpg) of premium unleaded (1.4 TFSI). This means that the A3 1.6 TDI emits just 109 grams of CO2 per kilometer (175.42 g/mile). With regard to the A3 1.4 TFSI, emissions amount to 124 g/km (199.56 g/mile).

The A3 1.6 TDI is powered by a four-cylinder TDI, which delivers 77 kW (105 hp) at 4,400 rpm from a displacement of 1,598 cc and – between 1,500 and 2,500 rpm – steadily transmits 250 Nm (184.39 lb-ft) of torque to the crankshaft. In conjunction with the S tronic, the TDI propels the three-door A3 from 0 to 100 km/h (0 to 62.14 mph) in 11.7 seconds en route to a top speed of 194 km/h (120.55 mph).

The A3 1.4 TFSI delivers 92 kW (125 hp) from a displacement of 1,390 cc; its maximum torque is 200 Nm (147.51 lb-ft) between 1,500 and 4,000 rpm. In conjunction with S tronic, this vehicle accelerates from 0 to 100 km/h (62.14 mph) in 9.3 seconds and tops out at 203 km/h (126.14 mph).

Also standard in both A3 models is an on-board energy-recovery system. During braking and coasting phases, this intelligently controls the alternator to recover energy, which is temporarily stored in the battery. This energy is then fed back into the electrical system during acceleration – thus reducing the load on the alternator. That saves fuel. The energy-recovery system and the start-stop system unleash their potential in particular in urban-driving conditions – precisely where most customers drive every day.

Audi will begin selling the A3 1.6 TDI and the A3 1.4 TFSI as a three-door and as a Sportback in November 2009. Prices for the 1.4 TFSI remain unchanged at €23,700 (3-door) and €24,600 (Sportback). The new 1.6 TDI with S tronic will sell at a base price of €25,500 for the 3-door and €26,400 for the Sportback.

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