Audi's second-generation aluminum car will prove out production process for the 2003 A6 midsize sedan -- and high volumes.

Back in 1976, VW Chairman Ferdinand Piech, then head of development for Audi, paid a visit to the Coors plant in Colorado to look at the production of aluminum beer cans. It's taken the best part of a quarter century to go from cans to cars, but Piech's vision of a high volume, mass produced aluminum automobile has moved a step closer with the launch of the Audi A2.

The A2 is Audi's second aluminum intensive vehicle. The first, the limited volume A8 luxury sedan launched in 1994, pioneered the productionization of Audi's innovative aluminum space frame (ASF) technology. The A2 takes lessons learned from the A8, and moves ASF technology downmarket for consumers and across the supplier chain. It will be built in four times the volume of the A8, and be used to prove out production processes for the 2003 Audi A6, which is currently planned to use ASF construction.

With prices starting from the equivalent of $22,000 in Britain, the A2 is an expensive small car -- about the same price as the larger 1.6L VW Golf -- even though in absolute terms, it is the world's most affordable aluminum intensive vehicle. What's crucial, however, is the A2 delivers on the much vaunted promise of aluminum autos, offering lower weight, better fuel economy and fewer emissions without compromising performance, comfort or safety. In this context the A2's sporty handling, funky styling and superb build quality are bonuses.

The genesis of the A2 dates back to 1991, when Piech announced that an affordable production car capable of fuel consumption of 3.0 litres per 100 km (about 80 mpg) should be feasible by 2000. That goal, Piech insisted, could not be achieved simply through powertrain and transmission improvements. He calculated that both vehicle mass and rolling resistance would have to be cut by 35%. It was against this background that the product specification of the A2 was determined.

By definition, then, the A2 was to be an efficient and roomy small car, with lightweight construction and a low coefficient of drag (Cd). Audi engineers calculated that a 10% reduction in vehicle weight translated to a 5% reduction in real world fuel consumption, while a 1% reduction in the coefficient of drag meant a 2% reduction in fuel consumption. Baseline modeling suggested a vehicle weighing 1,815 pounds and with a 0.25 Cd, powered by a 1.2L direct injection turbodiesel, could achieve the 3.0 liters/100 km fuel consumption bogey, with acceptable performance and driveability.

These are in fact the parameters for the fuel economy leader version of the A2 due next fall (see sidebar), but initially the car is being launched with 1.4L gasoline and the 1.4L TDI direct-injection turbodiesel engines. Weighing 1,969 pounds and 2,178 pounds, respectively, and capable of returning 47 mpg and 66 mpg, these are still light and efficient by conventional small car standards. Tougher safety laws and consumer demand for higher feature content mean the weight of a typical "C' segment car has increased by up to 25% over the past 15 years, with an average 45 to 50 mpg diesel-engined model now tipping the scales at 2,640 pounds.

The 1.4L 4-cylinder gasoline engine is a low-friction variant of the dohc, 16-valve powerplant used in VW's "B" segment Polo. It develops 74 hp at 5,000 rpm, and 93 lb-ft of torque at 3,800 rpm, driving the front wheels through a magnesium-cased 5-speed manual transmission. Claimed fuel consumption of 47 mpg is partly due to the low idle speed of just 680 rpm. The gasoline A2 is a lively performer, accelerating from 0 to 62 mph in 12 seconds, and reaching a top speed of 108 mph.

The 1.4L TDI is a 3-cylinder unit that shares the same bore centers as the new 4-cylinder Golf DI diesel. This enables the engines to be built on the same line. The TDI also develops 74 hp, but at 1,000 rpm lower than the 1.4L gas engine. A key feature of the TDI is a new high-pressure Bosch fuel injection system, which permits injection pressures of up to 29,725 psi (2,050 bar) and helps the engine achieve its peak torque of 143 lb-ft at just 2,200 rpm. As a result, the 66 mpg 1.4L TDI pulls strongly in the mid-range, and delivers similar performance to the petrol version -- 12.3 seconds 0 to 62 mph and 108 mph top speed -- despite being 209 pounds heavier, due to its cast-iron block, aluminium transmission casing and more robust gear clusters and axles.

Where It Beats Mercedes

The A2's front suspension is MacPherson strut with forged steel wishbones, while at the rear is a hydroformed torsion beam axle. Steering is electro-hydraulic power assisted rack and pinion, with the electric motor modulating the hydraulic pressure in the system on the basis of steering wheel angular velocity and vehicle speed. Audi claims the system can be delivered and installed as a ready module, and encoded on line to give vehicle-specific steering characteristics, reducing complexity and cost.