The new Audi Sportback concept launched at Detroit is described as a seamless blend of sports coupe desirability and five-door hatchback practicality. The sleek five-door GT is the latest in a long line of Audi design studies, many of which have transferred virtually unchanged to the production line, and not only offers a glimpse of Audi's future design vocabulary, but also raises the stakes with a new 47mpg TDI engine featuring the world's cleanest diesel technology.
As its name suggests, the Audi Sportback concept is a variation on the theme first defined in the Audi range by the A3 Sportback, with its combination of sports hatch styling and five-door versatility, and signals the brand's intention - as previously demonstrated by the A1 Sportback concept - to dramatically expand its line-up of Sportback models.
Power for the coupe comes courtesy of a new version of the acclaimed 3.0 liter V6 TDI. In its latest guise, this advanced unit can lay claim to offering the world's cleanest diesel technology thanks to numerous new efficiency optimization measures that not only give it the potential to provide up to 47.8mpg, but also to meet the emissions limits of all 50 US states as well as the forthcoming EU6 standard.
These measures include a downstream exhaust emission control system, which by injecting a biological additive called AdBlue upstream of the DeNOx catalytic converter helps to reduce harmful nitrogen oxide emissions by up to 90%, and unique combustion chamber sensors that enable even more precise regulation of the combustion process - another world first for Audi.
More familiar components, including the piezo common-rail injection system, efficient exhaust gas recirculation, optimized turbocharging and a regulated diesel particulate filter also help to reduce raw engine emissions.
Compared with the fleet average of the gasoline engines typically found in the US, the TDI boasts a fuel-efficiency advantage of up to 40%. The diesel technology thus makes a greater contribution than any other type of engine to reducing the consumption of fossil fuels. Audi will introduce this engine in the US and Europe during 2009.
As in the US version of the Audi Q7 3.0 TDI, the V6 produces 225hp and 406 lb-ft of torque in the Audi Sportback concept. Helped by its relatively low 3960 lb kerb weight and slippery 0.30 drag coefficient, it translates into a 0-62mph acceleration time of less than 7sec, and a top speed of 152mph. Power is transferred to the wheels via Audi's new seven-speed S tronic twin-clutch transmission, and is contained by the quattro permanent all-wheel-drive system.
For the first time in an Audi powered by a longitudinally-mounted engine, the Sportback features electromechanical power steering with a pump that consumes energy only when the wheel is turned, and not in the `straight-ahead' position. This `on-demand' approach also applies to the fuel pump, which uses less energy by activating only when there is a demand for fuel.
The already efficient S tronic twin-clutch transmission has also been enhanced by transmission oil heating which reduces internal friction by bringing the gearbox up to operating temperature much earlier. And in a similar vein, an innovative temperature management system brings the TDI up to its most efficient operating temperature more quickly by diverting part of the coolant flow.
When coasting, the Audi Sportback concept - like the Audi A4 and Audi Q5 production models - recuperates energy. This boosts the output of the alternator and is used to charge the battery. This energy, which in effect costs nothing to recover, is fed back into the vehicle's electrical system when needed. An automatic start-stop system shuts the TDI down to save energy when waiting at a traffic signal.
And when on the move, tires optimized for low rolling resistance cut fuel consumption significantly without impacting on performance.
The Audi Sportback concept show car takes the basic architecture and many components of its suspension from the brand's latest and most successful model family: the A4/A5 model series. The new five-link front suspension makes a major contribution to the car's dynamic character, and by moving the differential further forward and the clutch further back, the design engineers were able to reposition it further forward for optimal weight distribution.
The A4 and A5 also donate their Audi drive select adaptive dynamics system incorporating CDC (continuous damping control) shock absorbers whose operation can be continuously varied. The control unit selects the optimum damping force for the current driving situation, for instance firmer damping to prevent body roll and pitch when cornering fast or braking, or lower damping force where the surface is uneven.
The Audi Sportback concept is equipped with ceramic brakes on all four wheels for effective deceleration even under the most demanding conditions. Compared with conventional steel rotors, ceramic brakes not only last four times longer, up to 186,411 miles, but also offer high resistance to fading. The significant reduction in weight also leads to advantages in terms of comfort and handling, thanks to reduced unsprung masses.
On the front axle, 380mm ceramic discs are fitted in combination with 21" wheels. The rear rotors have a diameter of 356mm. The elaborate cooling ducts for the rotors ensures optimal cooling. Firm grip on the rotors is guaranteed at the front by six-piston monoblock aluminum brake calipers, and at the rear by floating calipers.
As with the exterior, the interior of the Audi Sportback concept is characterized by the emphasis on horizontal lines and large surfaces. This is especially true of the wide centre console - stretching from the dashboard to the rear. The flat display of the MMI system is realized as a retractable system in the show car. When the ignition is activated, it extends horizontally from a slot above the central air vents before moving in an elegant arc into a vertical, easy-to-read position.
The large glass roof underscores the width and spaciousness, and the sumptuous oak blockboard trim and liberal use of leather - which envelops everything from the dashboard and headlining right through to the trunk - emphasizes the study's luxury grand tourer status.