Drivetrain

Typically for an Audi study, the Roadjet Concept too is powered by an engine that heralds the shape of things to come with its innovative technology. This applies in equal measure to the 300 bhp evolutionary version of the 3.2 six-cylinder FSI engine and the sporty Direct Shift Gearbox in conjunction with quattro permanent four-wheel drive.

The 3.2 V6 FSI – which features as a basic engine with an output of 255 bhp in the Audi A8, A6 and A4 – displays all the characteristics of an ultramodern petrol engine: FSI petrol direct injection with demand-controlled fuel supply, four valves per cylinder and highly effective exhaust emission control.

FSI engines develop superior power and dynamism to conventional units with indirect manifold injection – and they do so with a very high stand­ard of fuel economy. With this remarkable achievement, Audi is opening up a new dimension in the efficiency of standard petrol engines, demonstrating once again the brand’s proverbial “Vorsprung durch Technik”.

The FSI petrol direct injection system confirmed its unique potential in what must be the most challenging endurance test in the world: a power unit with FSI direct injection drove the Audi R8 to victory on four occasions in the Le Mans 24 Hours.

The evolutionary version that powers the Roadjet Concept includes two technologies that double the specific advantage of FSI technology. Because with a fixed intake manifold together with integral vacuum reservoir – as opposed to the variable intake manifold of the production version – the 3.2 FSI can be configured systematically as a sports engine.

The six-cylinder engine in addition features a new valve control principle by the name of Audi valvelift system. In the form of two-stage cam lift adjustment, it is able to vary the degree of valve opening according to load and engine speeds.

What this means in practice is that in flowing traffic, the engine produces a decidedly smooth, relaxing response to only moderate use of the accelerator pedal, with impressive pulling power in reserve that results in outstandingly low fuel consumption.

But as soon as the driver ups the tempo, the 3.2 engine reveals its qualities as a highly talented athlete. It responds with bite to even minimal movements of the accelerator and moves fleet-footedly right up to the speed dictated by the limiter, which only cuts in at 7,500 rpm. What is particularly remarkable is that the power output rises constantly virtually all the way up to that point.

This V6 engine delivers its maximum output of 220 kW (300 bhp) at 7,000 rpm; its peak torque of 330 Nm is available at 4,500 rpm. The Roadjet Concept 3.2 FSI accelerates to 100 km/h in 6.4 seconds, and its top speed is electronically governed at 250 km/h.

No less astonishing is the average fuel consumption of this evolutionary concept: the Roadjet Concept covers 100 kilometres on just 10.4 litres of Super Plus – despite the Roadjet Concept's higher weight and larger frontal area, this figure is a few tenths of a litre better than its production counterpart in the A4 3.2 quattro, which develops 45 bhp less!

The combination of FSI and Audi valvelift system unquestionably demonstrates how much potential Audi's petrol engines of the future will still be capable of mobilising, with a view to delivering even more driving fun and efficiency. And that future is not far off: the underlying technology is already so mature that it could start finding its way into production in a few months' time.

The sporty 7-gear Direct Shift Gearbox

The Audi Roadjet Concept is the first Audi model to feature a sporty Direct Shift Gearbox with twin clutch in conjunction with a longitudinally installed engine. It combines the advantages of a 7-speed manual gearbox with the qualities of a modern automatic transmission, thus providing a drive concept superior in every respect. The driver benefits from supreme agility and driving pleasure combined with harmonious and dynamic acceleration without interruptions to the flow of power from the engine.

This is coupled with good economy thanks to low fuel consumption, and convenient operation.

The basis for this new development is a three-shaft 7-speed manual gearbox which offers considerable variability in the selection of the transmission ratio. Thanks to the use of a twin multi-plate clutch with ingenious electro-hydraulic control, two gears can be engaged at the same time.

So how does the Direct Shift Gearbox work? During dynamic operation of the car, one gear is engaged. When the next gearshift point is approached, the appropriate gear is pre-selected but its clutch kept disengaged. The gearshift process opens the clutch of the activated gear and closes the other clutch at the same time with a certain overlap. The gear change consequently takes place under load, with the result that a permanent flow of power is maintained.

Incorporating optimum gearshift strategies, the control logic integrated in the transmission provides instantaneous, comfortable and smooth gearshifts that are virtually free of any jolts or judder. And by moving the gearshift lever in the manual gate or operating the standard-fit paddles behind the steering wheel, as on a racing car, the driver can actively influence the choice of gears and the gearshift point at any time.

quattro permanent four-wheel drive

quattro permanent four-wheel drive is a typical feature of all high-performance Audi models. Since revolutionising the car world when first unveiled 26 years ago, permanent four-wheel drive has long since found its way into virtually all vehicle categories – and not just at Audi. Almost one in three Audi cars sold is currently a quattro; by the end of 2005, around 2.5 million Audi vehicles with quattro permanent four-wheel drive had been built.

quattro ensures excellent traction and lateral stability and minimises the effect of propulsive power on the vehicle’s self-steering properties. This is a precondition of the car's tremendous cornering speeds and high dynamic stability.

A Torsen differential in the new Audi Roadjet Concept – with its longitudinally installed engine – automatically ensures the optimum distribution of power between all four wheels.

The name Torsen is a combination of the terms “torque” and “sensing”. The Torsen differential is a self-locking worm gear.

The advantage of this is that the locking action is only prompted by the driveline. Yet this type of differential accommodates differences in speed when the brakes are applied and when cornering. The power is normally split 40:60 between the front and rear axles, producing particularly dynamic self-steering behaviour. In extreme cases, up to 80 percent of the propulsive power can be diverted to one pair of wheels if slip is encountered.

The equipment and data stated here refer to the model range offered for sale in Germany. We reserve the right to make changes. Errors and omissions excepted.