2008 Audi TT 2.0 TDI quattro

Audi is once again setting standards, this time with the new Audi TT and its TDI engine—a model that combines pure sportiness and powerful performance with sensational efficiency. The Audi TT 2.0 TDI Coupe quattro and Audi TT Roadster 2.0 TDI quattro are the first series-production sports cars to feature diesel engines. It’s a compelling union:

The two-liter engine generates dynamic propulsion with 125 kW (170 hp) and 350 Nm (258.15 lb-ft) of torque, yet the TT Coupe and TT Roadster consume an average of only 5.3 liters and 5.5 liters of fuel per 100 km (44.38 mpg and 42.77 mpg) respectively—unparalleled in the sports car segment.

Audi is setting the pace with this synthesis of excellent dynamism and low fuel consumption, as it has done for many years: Since debuting in 1989 the TDI engines from the brand with the four rings have been paving the way for the world’s most successful efficiency technology and acting as trendsetters for the entire automobile industry. Today, these powerful, refined and highly fuel-efficient engines represent a modern, smart take on sportiness. The run of victories achieved by the Audi R10 TDI diesel race car at the Le Mans 24 Hours and in the American Le Mans Series are impressive evidence of the tremendous potential of this technology.

The dynamic diesel engines from Audi exert an exciting impact not just in racing but also in series-production models—and now indeed in a sports car. The TT Coupe quattro with the 2.0 TDI sprints from zero to 100 km/h (62.14 mph) in 7.5 seconds and achieves a top speed of 226 km/h (140.43 mph). The Audi TT Roadster, likewise equipped with quattro permanent all-wheel drive, requires only an extra tenth of a second for the standard sprint, and continues up to a top speed of 223 km/h (138.57 mph). Both versions serve as outstanding examples of the success of the Audi efficiency strategy, thanks to their fuel efficiency ratings of 5.5 liters per 100 km (42.77 mpg), a figure that corresponds to CO2 emissions of only 145 grams/km.

Powerful, refined and efficient: The 2.0 TDI

The new four-cylinder TDI engine (engine displacement = 1,968 cc) represents a fresh take on the all-round compelling qualities of the TDI concept. Designers of the dual-camshaft, two-liter model looked to its predecessor—the most-produced diesel engine in the world—and expanded upon its major strengths: driving pleasure, efficiency and refinement.

The new common rail injection system is equipped with highly modern piezo injectors, whose eight-hole injection nozzles can perform up to five distinct injection sequences per cycle. This fine degree of modulation creates a modest pressure increase in the combustion chambers, resulting in a significantly reduced noise level. The system pressure of 1,800 bar allows fuel to form a fine dispersion, enabling precise, highly efficient combustion.

The turbocharger is also part of a new generation and operates with adjustable vanes that allow torque to build up rapidly. The positions of swirl flaps on the intake manifold are controlled by electric motors in order to adapt the flow of air to the current load and engine speed. The geometry of the engine’s pistons has been modified, and the acoustics of the camshaft drive belt have been overhauled. Just as they did in the preceding model, two balancing shafts reduce the vibrations arising in the crankshaft drive.

The cumulative result of this progress is a high maximum engine speed of 5,000 rpm and, most importantly, improved thermodynamics in the combustion chambers. What this means is that the engine can run on up to 60 percent recycled exhaust that has been thoroughly cooled by the radiator. This results in a drastic reduction in untreated NOx emissions, with the 2.0 TDI already meeting the threshold values of the upcoming Euro 5 standard.

Dynamic road performance

The 2.0 TDI in the Audi TT Coupe and the Audi TT Roadster delivers 125 kW (170 hp) at 4,200 rpm and sends a full 350 Nm (258.15 lb-ft) of torque to the crankshaft at engine speeds between 1,750 and 2,500 rpm. Operating quietly and generating little in the way of vibration, this model delivers a hefty amount of power at the lowest rpm levels and is highly responsive to input from the gas pedal. Its supreme power development lends this engine its own unique, fascinating character—that of a muscular, smart sports engine.

The Audi TT Coupe 2.0 TDI quattro easily leaves the gasoline-powered competition behind when accelerating from a standstill. It sprints from zero to 100 km/h (62.14 mph) in just 7.5 seconds and never looks back until it reaches 226 km/h (140.43 mph). The TT Roadster accelerates to 100 km/h (62.14 mph) in 7.7 seconds and keeps going up to 223 km/h (138.57 mph).

These models—the world’s first diesel sports cars—consume an average of only 5.3 liters and 5.5 liters of fuel per 100 km (44.38 mpg and 42.77 mpg) respectively, which corresponds to CO2 emissions of a mere 140 g/km and 145 g/km. In so doing, they are setting a benchmark that represents a veritable quantum leap in the sports car segment. With the TDI engine in the TT series, Audi once again establishes its leading role on the diesel market. The brand with the four rings is advancing progress and starting at the top.

In keeping with the theme of sporty performance, Audi has combined its two diesel-engine sports cars with highly effective manual six-speed transmissions whose short lever travel allows the driver to shift quickly, easily and precisely. The housings for these transmissions are made of lightweight, high-tech magnesium materials. Relatively long final transmission ratios have been employed to bring the drivetrain in line with the character of the TDI engine.

In light of their high torque values, Audi is equipping both of its new TT models with quattro permanent all-wheel drive. The heart of this system is an electronically controlled, hydraulically activated multi-plate clutch, which is located in the rear of the vehicle for improved weight distribution. This clutch generally distributes up to 85 percent of the engine power to the front axle and 15 percent to the rear axle; in extreme situations it can divert up to 100 percent of the power to either axle.

The overall concept: An exercise in uncompromised sportiness

Consistent efforts to reduce vehicle weight are also part of the efficiency strategy pursued by the brand with the four rings. Both sports cars are very lightweight: the 2 + 2-seater TT Coupe weighs only about 1,370 kilograms (3020.33 lbs) when empty, while the two-seater TT Roadster with soft top weighs roughly 1,415 kilograms (3119.54 lbs). Underlying these low weights is an innovative hybrid body construction developed by Audi. Front components are made of aluminum and utilize Space Frame technology; rear components are made of steel. This solution guarantees that the frame is as rigid as possible and optimizes load distribution between the axles.

The Audi TT Coupe and TT Roadster are dynamic, emotion-packed sports cars. As was the case with preceding models, these cars are impressive for their powerful design, whose dynamic flow continues on into the interior. The cockpit contains multiple nods to the circle motif, and the sports steering wheel with its flat-bottomed rim fits the driver’s hand like a glove. The sport seats are deep-set, providing a sporty seated position and firm lateral support. The backs of both rear seats fold down in the TT Coupe, making the trunk space grow from 290 to 700 cubic liters (10.24 – 24.72 cubic ft). The Roadster (250 liters, 8.83 cubic ft) comes with a practical load-through hatch upon request.

The sports suspension likewise offers extraordinarily dynamic features. The front suspension is pivoted on an aluminum subframe and has a wide track measuring 1,572 millimeters (61.89 inches).

A highly precise rack-and-pinion steering system with a direct steering ratio provides an intimate link between the driver and the road. Power steering with servo assist, which decreases as speed increases, is generated by an electromechanical drive that is even more efficient than a hydraulic pump.

The coil springs and shock absorbers in the four-link rear axle are situated in separate areas. The links are also finely differentiated: The layout of the trailing links, which absorb the propulsive and braking forces, is relatively soft to promote a comfortable ride. The connections to the three transverse links per wheel, on the other hand, are rigid in order to direct transverse forces into the body with precision.

The Audi TT Coupe 2.0 TDI quattro and Audi TT Roadster 2.0 TDI quattro roll on 16-inch, cast aluminum wheels fitted with 255/55 R16 tires. Behind the wheels are large disk brakes with pads that develop large coefficients of friction. The ESP stabilization program supports the neutral to slight understeering feel of the TT—the finishing touch on an overall portrait of exciting dynamics, exhilarating driving pleasure and stability you can count on.

Audi magnetic ride, a high-tech shock-absorber system available as an option, is an adaptive system that resolves the traditional conflict of interests between comfort and handling. A magneto-rheological fluid circulating in the shock absorbers changes the direction of the magnetic particles within milliseconds when electricity is applied; this alters the overall characteristics of the fluid and, in turn, modifies the damping characteristic. The driver can choose between “Normal” and “Sport” programs by flipping a switch.

Equipment makes a statement of refined style

Standard equipment for both of the new TT models reflects the sporty character and refined style of the series. Faux aluminum accents add a shine to gray inlays and various other components in the interior. The sports steering wheel comes with a Nappa leather cover. The climate control system (standard for the TT Coupe) regulates heating and ventilation in response to the level of sunlight. The driver information system and chorus audio system round out the standard equipment.

A wide array of high-tech equipment is available as options, including a highly modern generation of audio devices, electrically adjustable front seats, the adaptive light dynamic cornering light system and two navigation systems with a user interface based on the Audi MMI concept—a cut above the competition.

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The engine

Audi is setting the standard once again, this time with the new Audi TT and its TDI engine – a model that blends purist sportiness, powerful performance and sensational efficiency. The Audi TT Coupe 2.0 TDI quattro and Audi TT Roadster 2.0 TDI quattro are the first series-production sports cars in the world to use a diesel engine as their power source. A fascinating combination: The new two-liter, four-cylinder engine delivers dynamic thrust, with a power output of 125 kW (170 hp) and 350 Nm (258.15 lb-ft) of torque.

The TT Coupe quattro with the 2.0 TDI sprints from zero to 100 km/h (62.14 mph) in only 7.5 seconds and achieves a top speed of 226 km/h (140.43 mph). The Audi TT Roadster, likewise featuring quattro permanent all-wheel drive, takes just two-tenths of a second longer in the standard sprint discipline and has a top speed of 223 km/h (138.57 mph). The Coupe consumes on average just 5.3 liters of fuel over 100 km (44.38 mpg), representing CO2 emissions of only 139 grams/km; the figure for the Roadster is 5.5 l/100 km (144 grams of CO2/km). With the TDI in the TT series, Audi once again establishes its role as trendsetter on the diesel market. The brand with the four rings is pushing back the frontiers – starting at the very top.

The new four-cylinder TDI with its capacity of 1,968 cm3 signals the advent of a new generation of dynamic, ultra-efficient Audi diesel engines. It interprets the consistently impressive qualities of the TDI concept in a fundamentally new way. The two-liter power unit, featuring two camshafts, builds on the strengths of its predecessor, once the most-manufactured diesel engine in the world – high pulling power, impressive efficiency and refinement.

The new common rail injection system, run by one of the most advanced control units on the market, features ultramodern piezo injectors. Its eight-hole injectors can achieve up to five separate injection processes per combustion cycle. This fine-tuned approach produces a gentle pressure increase in the combustion chambers, decisively reducing the noise level. The single-piston high-pressure pump develops a system pressure of 1,800 bar. This allows fuel to form a fine dispersion, enabling precise, highly efficient combustion.

The turbocharger, too, belongs to a new generation. For a swift torque buildup it operates with adjustable vanes, and a special damper reduces its vibration. The engine’s intake manifold houses swirl flaps that generate a tumbling action in the inflowing air; electric motors regulate the flaps’ position so that this tumble is always adapted perfectly to the load and engine speed. The geometry of the engine’s pistons has been optimized, and the acoustics of the camshaft drive belt overhauled. Two balancing shafts reduce the second-degree inertial forces produced by the crankshaft drive.

High exhaust gas recirculation: low nitrogen oxide emissions

The cumulative result of this progress is a high maximum engine speed of 5,400 rpm and, most importantly, a significant improvement in thermodynamics in the combustion chambers. What this means is that the engine can run to a very large extent on recirculated exhaust gas that has been thoroughly cooled by the radiator. The cooler combustion process involving less oxygen drastically reduces engine emissions of nitrogen oxide.

Although the high exhaust gas recirculation rate is in and of itself detrimental to engine efficiency, in typical Audi style the engineers averted any undesirable increase in consumption and in fact turned this state of affairs to their advantage through intensive fine-tuning.

The 2.0 TDI in the Audi TT, with a compression ratio of 16.5:1, delivers 125 kW (170 hp) at 4,200 rpm. It puts a hefty 350 Nm (258.15 lb-ft) onto the crankshaft at engine speeds ranging from 1,750 to 2,500 rpm – the range where power really makes a difference to driving.

The four-cylinder power unit runs with little vibration and responds intently to the accelerator. Its superlative pulling power is available at virtually every engine speed, from rock-bottom upwards. It gives the 2.0 TDI an utterly distinctive, strong character – that of a beefy, clever sport engine.

The road performance reflects this character. The Audi TT Coupe 2.0 TDI quattro easily leaves behind the competition with equivalent gasoline engines in midrange acceleration and it sprints from zero to 100 km/h (62.14 mph) in just 7.5 seconds, not looking back until it reaches 226 km/h (140.43 mph). The TT Roadster accelerates to 100 km/h (62.14 mph) in 7.7 seconds and keeps going up to 223 km/h (138.57 mph).

The TT Coupe and TT Roadster achieve average fuel consumption of just 5.3 and 5.5 liters of fuel per 100 km (44.38 and 42.77 US mpg) – equating to emissions of 139 and 144 grams of CO2/km respectively. In so doing, Audi is setting a benchmark that represents a veritable quantum leap in the sports car segment. The operating range of over 1,100 km (683.51 miles) on a single tank of fuel (Coupe) expresses this superiority in a directly tangible and impressive way. The Audi slogan "But where’s the tank?" from the classic TV commercial now has equal validity for its sports cars.

The TDI version of the TT easily shrugs off the challenge from its gasolineengined competitors, too, when the figures that really count are closely scrutinized. Its specific output is 63.5 kW (86.4 hp) per liter of engine capacity, and its specific torque is all of 177.8 Nm (131.14 lb-ft) per liter. But the most impressive ratio is power to fuel consumption and CO2 emissions: At just 0.90 kW (1.22 hp) per gram/km, the TT 2.0 TDI quattro is truly in a league of its own when it comes to efficiency.

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The drivetrain

In keeping with the theme of sporty performance, Audi has equipped its dieselengine sports cars with highly effective manual six-speed transmissions whose short lever travel allows the driver to shift quickly, easily and precisely. The housings for these transmissions are made of lightweight, high-tech magnesium. Relatively long final transmission bring the drivetrain into line with the character of the TDI engine.

In light of their immense torque of 350 Nm (258.15 lb-ft), Audi is equipping both of its new TT models with quattro all-wheel drive as standard. This decisively improves traction, slip-free acceleration, drivability, stability and straight-line running in all weather conditions.

The nerve center of the quattro drive in the TT is an electronic-control, hydraulically actuated multi-plate clutch located at the end of the propshaft at the vehicle’s rear end – a position that improves the weight distribution. It distributes the torque continuously between the front and rear wheels depending on the driving situation. Thanks to a new pressure reservoir, the clutch works twice as fast as before, within a matter of milliseconds.

The chassis

The sports suspension likewise offers extraordinarily dynamic features. The front suspension – a classic McPherson layout – is pivoted on an aluminum subframe. A highly precise rack-and-pinion steering system with a direct steering ratio provides an intimate link between the driver and the road. Power steering with servo assist, which decreases as speed increases, is generated by an electromechanical drive far more efficient than a hydraulic pump.

The coil springs and shock absorbers in the four-link rear axle are situated in separate areas. The control arms, too, are carefully configured: The trailing links, which absorb the propulsive and braking forces, have a relatively soft characteristic to promote ride comfort. The connections to the three transverse links per wheel, on the other hand, are rigid in order to direct transverse forces into the body with precision.

Audi equips the Coupe and Roadster with 16-inch cast alloy wheels as standard, fitted with size 225/55 R 16 tires. Behind the wheels are large disk brakes with pads that develop high coefficients of friction. They measure 312 millimeters (12.28 in) at the front and 286 millimeters (11.26 in) at the rear; the front disks are ventilated. The ESP electronic stabilization program is optimized for a dynamic style of driving. A brief press of a button at lower speeds – e.g. when driving on snow chains – is all it takes to increase wheel slip. A longer press of the button takes the TT driver into a second, sporty operating plane in which the ESP permits controlled sideslip angles. The brakes intervene somewhat later than in normal operation and engine manipulation is suppressed.

Audi magnetic ride, a high-tech shock-absorber system available as an option, is an adaptive system that resolves the traditional conflict of interests between comfort and handling. A magneto-rheological fluid circulating in the shock absorbers changes its flow properties within milliseconds when a voltage is applied; this, in turn, alters the damping characteristic. The driver can choose between "Normal" and "Sport" programs by flipping a switch.

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The body and interior

The intelligent lightweight design of the Audi TT 2.0 TDI quattro is a key factor in its sporty performance. The 2+2-seater Coupe tips the scales at only 1,370 kilograms (3,020.30 lb) when unladen, with the two-seater Roadster weighing only slightly more at 1,415 kilograms (3,119.51 lb). The open sports car has a classic sport top – this is lightweight, keeps the center of gravity low, blends harmoniously with the overall styling, and occupies minimal space when folded down.

The low weight is the result of an innovative hybrid-design body developed by Audi. The forward structure is made of light aluminum components assembled using the space frame principle; steel is used for the rear structure. This solution guarantees that the frame is as rigid as possible and optimizes load distribution between the axles. The bodyshell of the Coupe weighs 206 kilograms (454.15 lb); it weighs a bit more in the case of the Roadster – 251 kilograms (553.35 lb) – in view of the special reinforcements it incorporates.

Fascinating: the design

Both body versions present a fascinatingly powerful, emotional design. The 4,178 millimeter (164.49 in) long body comes across as muscular and dynamic. The nose end is dominated by the large single-frame grille, and there is an integral automatically extending spoiler at the rear. Subtle quattro badges identify it as a fundamentally all-wheel-drive vehicle. With drag coefficients of 0.30 (Coupe) and 0.32 (Roadster), Audi demonstrates how good design can produce a low drag coefficient, which translates into a higher top speed and better fuel efficiency.

The flowing dynamic style is echoed in the car’s interior. The driving area with its clear-cut instruments makes reference to the classic circle motif, as do the air vents and rotary controls for the automatic air conditioning, which has been integrated into the center console angled slightly towards the driver. The sport steering wheel with the flat-bottomed rim rests snugly in the hands. Perfect ergonomics and uncompromisingly high standards of build quality are a question of honor for Audi.

The height-adjustable sport seats are deep-set, providing a sporty seated position and firm lateral support. The backs of both rear seats fold down in the TT Coupe, making the trunk space grow from 290 to 700 cubic liters (10.24 – 24.72 cubic ft). The TT Roadster (250 liters (8.83 cubic ft) whether the hood is up or down) can also be supplied with the option of a useful load-through facility with removable ski bag.

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The equipment

The standard equipment highlights the sporty character of both diesel-engined TT versions. The interior is accentuated by aluminum-look components in conjunction with inlays in Micrometallic gray. The sports steering wheel comes with a Nappa leather skin. The automatic air conditioning (optional for Roadster) regulates the heating and ventilation.

In the event of an accident there are two front and head/thorax airbags ready to protect each occupant of the front seats; the specially shaped seat backs and head restraints shield the driver and front passenger in a rear-end collision. Electric windows and exterior mirrors, the driver information system, front fog lights and the chorus audio system round off the standard specification.

The equipment options include an extensive range of high-tech features. These include the electrically adjusted front seats, the dynamic cornering light system by the name of adaptive light, a navigation system that shares the same operating principle as Audi’s incomparable MMI concept, and an ultramodern generation of audio systems. In addition to various leather equipment lines, three leather packages are available.

The TT Coupe 2.0 TDI quattro and TT Roadster 2.0 TDI quattro will be arriving at dealers in the first half of the year. The enclosed sports car version has a starting price of EUR 34,850 and its open-top counterpart EUR 35,900.

TDI engines in motor racing

Since first appearing in 1989, Audi’s TDI engines have been setting trends for the rest of the automotive industry to follow. With their power, refinement and efficiency, they have come to represent a modern, smart interpretation of sportiness. The run of victories celebrated by the Audi R10 TDI diesel race car at the Le Mans 24 Hours and in the American Le Mans Series is impressive evidence of the tremendous potential of this technology.

The Audi R10 TDI has been blazing a trail since early 2006 – with its twelvecylinder diesel engine it has entered an entirely new dimension. The 5.5 liter TDI is a race engine of superior pedigree. Its torque far surpasses that of any gasoline engine, developing more than 1,100 Nm (811.32 lb-ft). At nominal engine speed it delivers over 650 horsepower, producing a top speed of around 330 kilometers per hour (205.05 mph).

The only minor problem encountered right at the start was due to the specific nature of the twelve-cylinder TDI – its very quiet running. The drivers of the open-top prototype – including multiple Le Mans winners such as the Dane Tom Kristensen and the German Frank Biela – had to get used to this fundamentally different attribute. Whereas they had previously been able to rely on the engine’s sound as a guide to its performance, above a given speed it was now no longer audible.

They soon adapted to the new situation, and the mighty diesel engine has since been demonstrating its strengths with resounding success. Among its virtues is fuel efficiency. Compared with its predecessor, the already very efficient R8 with gasoline direct injection, the Le Mans version of the R10 TDI was markedly more economical. Furthermore the Le Mans circuit, with its long straights and scope for 75 percent use of full throttle, does not provide a true reflection of its strengths. Fewer stops for refueling mean faster times – so high efficiency was the key to two successive victories in the tradition-steeped French endurance race. In 2006 Frank Biela, Emanuele Pirro (Italy) and Marco Werner (Germany) emerged as clear winners, completing 380 laps equivalent to 5,187 km (3223.05 miles) at an average speed of 215.409 km/h (133.849 mph). The same team of drivers again won in 2007, even though the organizers had capped the tank capacity of the R10 TDI. In difficult weather conditions Biela/Pirro/Werner clocked up 369 laps at an average speed of 209.152 km/h (129.961 mph).

The R10 TDI embarked on an impressive string of victories in the American Le Mans Series in the first half of 2006 – it won all eight heats in which it participated during the season. It again went from triumph to triumph in 2007, clinching the Constructors’ Trophy in the large LMP 1 category. The 2008 season got under way in mid-March, and Audi again relishes this sizeable challenge.