Concept: Audi A1 e-tron & Audi A8 HybridDocument Transcript
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Audi show cars for the 2010 Geneva Motor Show
Audi A1 e-tron 2
Audi A8 hybrid 8
The equipment and data specified in this document refer to the model range offered in
Germany. Subject to change without notice; errors and omissions excepted.
Audi A1 e-tron – zero-emissions in the city
Audi is expanding its new e-tron model family step by step. The A1 e-tron,
which Audi is showing at the Geneva Motor Show, is an innovative Mega
City Vehicle (MCV). Like its sports car brothers, it has an electric drive
system. The A1 e-tron has a range of more than 50 kilometers (31.07 miles)
in city traffic, and its peak output of 75 kW (102 hp) also makes the it very
fun to drive. A compact internal combustion engine recharges the battery
when its energy is depleted.
The powerful front-mounted, transverse electric motor thrusts the A1 e-tron
forward with authority. The car sprints from a standing stop to 100 km/h
(62.14 mph) in only 10.2 seconds on its way to a top speed of more than
130 km/h (80.78 mph). The compact MCV is a zero-emissions vehicle for the first
50 kilometers (31.07 miles) that it is underway, such as in city traffic. The battery
comprises a package of lithium-ion modules mounted in the floor assembly in
front of the rear axle.
A small, single-rotor Wankel engine is used in this near-series concept vehicle to
increase the range in exceptional circumstances. This “range extender” powers a
generator that produces 15 kW of charging power. If the range extender is used
to recharge the battery, the A1 e-tron can cover an additional 200 kilometers
(124.27 miles) of range. According to a draft standard for the computation of fuel
consumption for range extender vehicles, this represents a fuel consumption of
1.9 l/100 km (123.80 mpg) – a CO2 equivalent of only 45 g/km (72.42 g/mile).
Thanks to its grown-up, sporty yet comfortable character, the Audi A1 e-tron
drives like a car from a larger class. The concept car rolls on 18 inch alloy
wheels. Many fine details in the interior document the Audi philosophy: The new
electric mobility requires absolute no sacrifices in terms of sportiness or comfort –
on the contrary – it stands for an innovative and smart form of driving fun.
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 (102 hp)
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 megacities 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
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 (102 hp) 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
center of gravity. Continuous output is rated at 45 kW (61 hp), with peak power of
75 kW (102 hp) available in short bursts. 150 Nm (110.63 lb-ft) of torque is
continuously available, and peak torque is 240 Nm (177.01 lb-ft).
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 center
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. In addition, 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
center of gravity and weight distribution. The battery pack is shaped like a T, with
the short “transverse beam” filling the rear section of the center 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 (330.69 lb).
The Audi A1 e-tron can drive 50 kilometers (31.07 miles) 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
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 liters (3.17 US gallons).
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
(154.32 lb). This weight also includes the special power electronics, the intake,
exhaust, and cooling unit, plus the insulation and the subframe.
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 (2,623.50 lb) delivers zero-emission
driving fun in a modern and sophisticated manner. The vehicle accelerates from
0 to 100 km/h (62.14 mph) in 10.2 seconds and has a top speed of more than
130 km/h (80.78 mph).
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 kilometers (124.27 miles).
According to the draft standard, the two different operating modes yield a fuel
consumption of only 1.9 l/100 km (123.80 US mpg), which corresponds to
CO2 emissions of 45 g/km (72.42 g/mile). 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 tires; the generous, “grown-up” interior; the excellent fit and finish;
and a multitude of high-end equipment.
The dark shade “ebony” dominates the interior. The seats – with stone gray
seams – and the headliner are in “Alabaster White.”
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 color 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 center 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
Audi presents the A8 hybrid as a technology concept at the Geneva Motor
Show. Its two engines – a 2.0 TFSI and an electric power unit – develop a
combined total of 180 kW (245 hp) and deliver 480 Nm (354.03 lb-ft) of
torque, enabling them to provide the confident driving performance of a
large six-cylinder engine. And combined with the advantages of electric
power, the consistent downsizing also pays substantial benefits in fuel
economy – with an average consumption of just 6.2 liters (37.94 US mpg)
per 100 km, corresponding to a CO2 value of 144 grams per km
The Audi A8 hybrid utilizes a parallel hybrid system – a highly efficient principle
that avoids any unnecessary friction and power losses. Interposed between the
four-cylinder gasoline engine, which delivers 155 kW (211 hp), and the eight-
speed tiptronic is a powerful electric motor. It develops 33 kW (45 hp) of power
and a very ample 211 Nm (155.63 lb-ft) of torque. The two power units together
develop a system power of 180 kW and 480 Nm (354.03 lb-ft). This enables the
Audi A8 hybrid to accelerate in 7.6 seconds from zero to 100 km/h (62.14 mph)
and to achieve a top speed of 235 km/h (146.02 mph).
The A8 concept car is a full hybrid. This means that it can be propelled by either
the gasoline engine or the electric motor alone – or by the combined power of
both. During coasting or braking, the electric motor acts as a generator that
converts kinetic into electric energy and recharges the battery. The hybrid drive
can propel the car on electric power alone at up to 65 km/h (40.39 mph) with a
range of over two kilometers – enough for urban stop-and-go traffic.
The efficiency standard – the Audi A8 hybrid
Power 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 (245 hp) of system power and 480 Nm (354.03 lb-ft) of
torque. This enables the Audi A8 hybrid to accelerate in 7.6 seconds from
zero to 100 km/h (62.14 mph) and to achieve a top speed of 235 km/h
(146.02 mph). Yet its average fuel consumption amounts to only 6.2 liters
(37.94 US mpg) 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 (211 hp) and 350 Nm (258.15 lb-ft); 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 flow-
rate-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 (45 hp) of power and 211 Nm (155.63 lb-ft) 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
liters (14.13 cubic feet)
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
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.
The Audi A8 hybrid, which weighs 1,885 kilograms (4,155.71 lb), drives as if it
had a big six-cylinder gasoline engine or a TDI under its hood. From zero to
100 km/h (62.14 mph) the vehicle accelerates in 7.6 seconds, and it can continue
to accelerate up to 235 km/h (146.02 mph). Yet its fuel consumption according to
the EU cycle is only 6.2 liters per 100 km (37.94 mpg), corresponding to
144 grams CO2/km (231.75 g/mile). 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
(40.39 mph) and for a distance exceeding two kilometers – 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
When the Audi A8 hybrid starts moving, both of its engines interoperate closely to
suit varying power demands. Above 65 km/h (40.39 mph) 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 gas, 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
(245 hp) and 480 Nm (354.03 lb-ft) endow the big sedan with enormous thrust.
The intermediate sprint from 60 to 120 km/h (37.28 to 74.56 mph) 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 tires.
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 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 "Powermeter" in addition shows the energy flow in the instrument cluster.