Audi show cars for the 2010 Geneva Motor Show

Audi A1 e-tron – electric driving in the city
The new e-tron model series from Audi will gain another new member at the Geneva Motor Show: The Audi A1 e-tron is a Mega City Vehicle (MCV) with an innovative drive technology. It comes equipped with a powerful electric motor for zero-emission driving in the city. There is also an internal combustion engine on board that recharges the battery in exceptional circumstances. The A1 e-tron is very agile thanks to the 75 kW peak power of its electric motor.
 
The technology of the Audi A1 e-tron
The e-tron model family from Audi is just a few months old, but it already has a number of members, for each of which Audi has chosen a different drive technology. The first e-tron, which debuted at the 2009 IAA in Frankfurt/Main, is a near-series high-performance sports car with electric motors for all four wheels. The study shown at the Detroit Motor Show in 2010 is a lightweight, compact two-seater with two electric motors on the rear axle.
 
The A1 e-tron now presents another approach – a compact electric car in the premium class. The four-passenger, two-door MCV city car was designed specifically for use in the metropolitan areas of Europe and North America and in the rapidly growing mega cities of Asia and South America. The Audi A1 e-tron always drives on electric power; its internal combustion engine is only used to recharge the battery in isolated cases.
 
The integration of the new technologies shows the holistic approach that Audi is pursuing with electric mobility. The objective is to use the energy with the lowest possible losses. The precise interaction of the components, their intelligent packaging, and the efficient management of the current flows are the product of the expertise that the company has developed in this area.
 
Audi has developed a proprietary thermal management system to keep the battery, the electric motor, and the power electronics within their respective ideal temperature windows. Behind the three e-tron models is a broadly diverse and modular technology platform that continues to grow very rapidly as Audi drives development forward.
 
The electric motor: 75 kW peak power
The synchronous electric motor of the Audi A1 e-tron is mounted transversely at the front of the car. Its low mounting position has a positive effect on the vehicle’s centre of gravity. Continuous output is rated at 45 kW, with peak power of 75 kW available in short bursts. 150 Nm of torque is continuously available, and peak torque is 240 Nm.
 
The electric motor sends its power to the front wheels via a single-speed transmission. The elegant, retractable selector lever on the console of the centre tunnel used to choose between “Drive,” “Reverse,” and “Neutral” was taken from the first Audi e-tron.
 
The power electronics are mounted in the engine compartment above the electric motor. The most important components are the pulse-controlled inverter, which serves as the controller between the electric motor and the battery; the DC converter, which connects the high-voltage network with the 14 volt electrical system; a breaker unit to protect the high-voltage components; and the charging
module.
 
The socket for the standard charging plug is located behind the rings in the single-frame grille of the Audi A1 e-tron. A fully depleted battery can be recharged in approximately three hours from the 380 volt grid. A display immediately adjacent to the plug-in connection shows the current charge status and the charging time remaining.
 
The concept of the innovative Mega City Vehicle requires the electrification of key auxiliaries. The refrigerant compressor of the climate control system, for example, is electrically powered by a high-voltage electric motor that supplies only the amount of power needed at the time. This increases system efficiency substantially compared to conventional concepts. Thanks to a special circuit, the climate control loop also functions as a heat pump that regulates the temperature of the cabin and the battery.
 
The power steering of the Audi A1 e-tron is electro-mechanical and thus particularly energy-efficient. An electronic brake system makes it possible to tap into the recuperation potential of the electric motors. A hydraulic fixed-caliper brake is mounted on the front axle, with two novel electrically-actuated floating caliper brakes mounted on the rear axle. These floating calipers are actuated not
by any mechanical or hydraulic transfer elements, but rather by wire (“brake by wire”). In addition, this eliminates frictional losses due to residual slip when the brakes are not being applied. Furthermore, the servo unit received a new, demand controlled electric vacuum pump.
 
The large electric motor powering the A1 e-tron can convert braking energy into electric current and feed it back into the electrical system. The high degree of recuperation benefits overall efficiency. The electric control actions are imperceptible to the driver, who notices only the familiar, precise, and perfectly controllable pedal feel.
 
The battery pack: a compact T arranged below the floor
The energy storage unit is arranged below the floor, where it is ideal for the centre of gravity and weight distribution. The battery pack is shaped like a T, with the short “transverse beam” filling the rear section of the centre tunnel and the “cross-beam” filling that area in front of the rear axle where the fuel tank is otherwise located. The 380 volt lithium-ion rechargeable battery has a nominal energy content of 12 kilowatt hours. It comprises 96 prismatic cells and weighs less than 150 kilograms.
 
The Audi A1 e-tron can drive 50 kilometres emission-free in city traffic on the powerful battery. On longer trips, the battery is recharged by a particularly compact internal combustion engine mounted below the luggage compartment.
 
The range extender
The A1 e-tron concept car has a Wankel engine as a range extender, but other compact concepts are also possible. The small single-rotor Wankel has a chamber volume of 254 cc and runs at a constant 5,000 rpm in its peak efficiency window. The electronics also consider navigation data such as the destination and route profile to automatically activate the range extender as needed. The driver can also turn the range extender on and off as necessary with the push of a button The fuel tank holds 12 litres.
 
The great strengths of the Wankel engine are the nearly vibration-free and quiet operation, the small dimensions, and the extremely low weight. Together with the generator, which is powered by the Wankel engine and produces 15 kW of electric power, the complete assembly weighs only around 70 kilograms.  This weight also includes the special power electronics, the intake, exhaust, and cooling unit, plus the insulation and the subframe.
 
Driving experience
The first defining impression that the driver of the Audi A1 e-tron gets is that of nearly total silence. Even the Wankel engine in the back can barely be heard when it is running.
 
The second characteristic perception is the power of the electric motor, nearly all of which is available instantly and thrusts the Audi A1 e-tron forward with authority. The innovative Mega City Vehicle, which despite its complex drive technology weighs only 1,190 kilograms and delivers zero-emission driving fun in a modern and sophisticated manner. The vehicle accelerates from 0 to 100 km/h in 10.2 seconds and has a top speed of more than 130 km/h.
 
The Audi A1 e-tron can also cover longer distances if the range extender charges the battery. The extra range, which is intended primarily for interurban driving, is 200 kilometres.
 
According to the draft standard, the two different operating modes yield a fuel consumption of only 1.9 l/100 km, which corresponds to CO2 emissions of 45 g/km. In electric mode, there are zero local CO2 emissions - the compact A1 e-tron is thus ecological and economical.
 
The third impression that the A1 e-tron makes is that of a larger car. The compact two-door boasts all of the strengths of the new A1 model series – the carefully tuned, sporty chassis with specially designed 18 inch alloy wheels and 215/35 R18 tyres; the generous, “grown-up” interior; the excellent fit and finish; and a multitude of high-end equipment.  
 
Design
The concept car in Geneva has a special “Aqua Mint, pearl effect” paint finish; the contrasting roof arch is offset in “High Gloss Steel dark.” As with the other two e-tron models, the 18-inch wheels with a 20-spoke turbine design convey the high-tech aspiration of the concept. The rear diffuser with aluminum trim lacks tailpipes. This emphasizes the width of the vehicle and suggests the low emissions. The two front fenders are emblazoned with the “e-tron” logo.
 
The “Aqua Mint, pearl effect” exterior colour carries over into the interior, where it adorns the door panels and the center console. The shift lever is a special leather-wrapped design; as is typical for the e-tron models, the start-stop button was placed in the front of the centre console. A specially designed battery cover at the front of the car and the range extender engine with its cooling fins displayed under a sheet of glass in the luggage compartment also serve to visually underscore the clean technology of the A1 e-tron. And because an innovative drive concept also calls for innovative information management, the concept car features a freely programmable instrument cluster with a virtual display surface and innovative display and operating concept.
  
The efficiency standard – the Audi A8 hybrid
Powered like a big V6, fuel economy like a modest four-cylinder unit – Audi presents the A8 hybrid as a technology concept at the Geneva Motor Show. Its two propulsion units – a 2.0 TFSI and an electric motor – develop a total output of 180 kW of system power and 480 Nm of torque. This enables the Audi A8 hybrid to accelerate in 7.6 seconds from zero to 100 km/h and to achieve a top speed of 235 km/h. Yet its average fuel consumption amounts to only 6.2 litres per 100 km – the CO2 equivalent is 144 grams per km.
 
The technology of the Audi A8 hybrid
The combustion engine of the Audi A8 hybrid is the 2.0 TFSI – a high-tech powerplant. This four-cylinder unit, which has been named “Engine of the Year” five times in a row since 2005, is an example of Audi’s downsizing philosophy. It combines direct fuel injection with turbocharging and the AVS (Audi valvelift system), which regulates the valve lift in two stages. In combination with the adjustable intake camshaft, the Audi valvelift system improves cylinder charging and ensures spontaneous and powerful torque build-up. The 2.0 TFSI delivers 155 kW and 350 Nm; the torque value remains constant from 1,500 to 4,200 rpm.
 
In the crankcase of the four-cylinder unit, which has a displacement of 1,984 cc, two balancer shafts offset second-order inertial forces to ensure virtually vibration-free and pleasantly quiet operation that goes well with the luxurious character of the A8. All components are optimized to minimize friction. The flowrate-regulated, pressure-controlled oil pump further reduces fuel consumption.
 
Electric motor with ample propulsive power
A hydraulically operated wet clutch links the 2.0 TFSI with the electric motor. Its control requires the utmost precision, and a great deal of know-how has been expended to achieve its smooth, precise and swift operation. The synchronous motor, which is continually excited, also serves as a generator that develops 33 kW of power and 211 Nm of torque. Its full power is available practically right from standstill and contributes to a sportily powerful start-up.
 
Since an electric motor also develops heat, its housing is furnished with cooling ducts. Interposed between the electric motor and the wheelset of the eight-speed tiptronic, which is controlled entirely by electronics, is an additional cut-out clutch. In conjunction with the electric unit, this functions as a torque converter. The propulsive power of both drive systems is applied to the road through the front wheels.
 
Lithium-ion technology – the battery
The energy storage system of the Audi A8 hybrid is mounted in the rear section. This state-of-the-art lithium-ion battery is more compact and weighs less than other types but is substantially more powerful. It is protected by a high-strength housing, and a ventilation module ensures that it always operated within the ideal temperature range. Yet the A8 hybrid also provides ample luggage space of 400 litres. 
 
Several subsystems that operate on engine power in a conventional car have been modified right from the start for use in the Audi A8 hybrid. The compressor in the climate control system runs entirely on electric power. The steering system is electromechanical as well. The brake booster, too, is supplied by a demand controlled electric vacuum pump. During electrical – i.e. recuperative – braking actions, a sophisticated control system ensures that the ABS and ESP functions operate properly.
 
The power electronics unit manages the interaction of the systems. Its pulse control inverter regulates the interplay of the battery and the electric motor. The DC-DC converter supplies power to users on the onboard network. The power electronics unit, which is connected to the battery and the electric motor by high voltage cables, is located in the engine compartment.
 
The smooth interaction of these components and their high level of integration attest to the specialized know-how Audi has accumulated. The technology architecture already provides a glimpse of a future production model – the Audi Q5 hybrid,  which will be introduced later this year.
 
Driving experience
The Audi A8 hybrid, which weighs 1,885 kilograms, drives as if it had a big six-cylinder petrol engine or a TDI under its hood. From zero to 100 km/h the vehicle accelerates in 7.6 seconds, and it can continue to accelerate up to 235 km/h . Yet its fuel consumption according to the EU cycle is only 6.2 litres per 100 km, corresponding to 144 grams CO2/km.
 
In city traffic, the hybrid drive uses about 20 percent less fuel than a conventional drive. Both the car’s performance and its fuel economy benefit substantially from a major advantage of the A8 model series – its lightweight aluminum body based on the Audi Space Frame principle (ASF).
 
The hybrid drive is designed for fully electric-powered driving up to 65 km/h and for a distance exceeding two kilometres – especially well-suited for driving in the city or residential suburbs. When conditions permit, the driver can also select the electric mode by actuating a separate e-key in the cockpit. Both the display screen of the instrument cluster and the large monitor of the MMI operating system on the dashboard present all momentary power flows in brilliant graphics.
 
When the Audi A8 hybrid starts moving, both of its engines interoperate closely to suit varying power demands. Above 65 km/h the combustion engine alone does all the propulsive work, while the electric motor supplies onboard users and recharges the battery.
 
When the driver lets up on the fuel, the combustion engine is disconnected from the drivetrain, so the Audi A8 hybrid ”sails”. In braking and slow-down phases, the e-motor functions as a generator – recuperating energy efficiently and feeding it into the battery.
 
When the driver floors the pedal, the engine management temporarily controls the entire system power, and now the electric motor is boosting power. 180 kW and 480 Nm endow the big sedan with enormous thrust. The intermediate sprint from 60 to 120 km/h in fifth gear for instance is accomplished in 7.5 seconds.
 
The Audi A8 hybrid is an extremely dynamic car – with a fuel efficiency that is setting new standards. This is especially true in everyday user activities. Even its looks betray the power of this near-production concept car with its big 21-inch wheels and their 265/35 tyres. Efficiency and sportiness are no paradox at Audi – they go hand in hand.
 
The design of the Audi A8 hybrid
This near-production concept car has 21-inch, two-colour wheel rims styled with highly three-dimensional surface areas. The exterior paint job of the A8 hybrid is in “Prism Silver” with “Spectra Flair” as an accent color – a rainbow effect that’s accentuated in reflected light along creases and seams on the body. The prominently located “hybrid” lettering on both front fenders leaves no doubt about what kind of car this is. The accentuation of its width by a prominent low horizontal spoiler edge and a chrome strip conveys the vehicle’s solid stance on the road.
 
The engine compartment cover with its high-gloss finish and the glass cover of the battery in the trunk also provide visual links to hybrid technology. And the illuminated doorsteps bear the “hybrid” insignia as an elegant touch to underscore the electric aspect whenever the doors are opened – using LED technology to minimize energy consumption.
 
The passengers also see the prominent hybrid logo displayed on the dashboard. The "Powermetre" in addition shows the energy flow in the instrument cluster.