Exagon Furtive-eGT - 2013
(from Exagon Press Release) Furtive-eGT, the concept
With its electric drivetrain and innovative solutions, the Furtive-eGT rewrites the ground rules for contemporary GT sports cars. Not in terms of performance alone, but in terms of the new driving sensations delivered by a grand tourer designed as an electric vehicle from A to Z.
An exceptional electric GT sports car
Exagon Motors set out to develop an exceptional electric sports car that would combine the best of their experience in electric motorsports (Electric Andros Trophy) with today’s cutting-edge technologies. The specifications drafted by Luc Marchetti, CEO of Exagon Motors, established clear objectives: the Furtive-eGT had to combine exceptional performance with real day-to-day driveability. To achieve this versatility, Exagon worked with a number of leading European partners who brought their expertise to the project from the outset: Siemens, Saft, Michelin and Nokia. The result: the most exciting GT sports car around.
Original technologies and leading partners
The Furtive-eGT combines an impressive sum of human expertise with technologies never before seen in cars. It is an innovator in all areas, from its latest-generation Siemens motors and Saft batteries to its carbon body, running gear developed with Michelin, three-speed gearbox with seamless torque delivery, acoustics by Focal and man/machine multimedia interface. The Furtive-eGT embodies a unique blend of expertise. No comparisons can be made with the existing market offering.
A GT made for the era of sustainable development
The Furtive-eGT is very much a car of its times, the era of digital cars and sustainable development, but it also reflects a long tradition in exceptional GTs. This long-haul traveller is a true 2+2, designed to comfortably seat four passengers with their luggage. The Furtive-eGT is designed as a versatile car, combining the ride and performance of a quality sports model with the comfort of a grand tourer.
A new sensory experience
The electric drivetrain delivers original driving sensations with the torque coming in immediately. With constant torque of 516 N.m between 0 and 5,000 rpm, the Furtive-eGT is capable of phenomenal acceleration, sprinting from 0 to 100 km in just 3.5 s, with a top speed limited to 250 kph. As well as savouring the silence of this impressive performance, owners can take pleasure in owning a car with zero carbon emissions. Looking beyond figures, this is an experience that everybody should enjoy at least once in their lives.
French spirit and style
Designed by Exagon MotorsTM, the Furtive-eGT is a car of classic, timeless beauty. It embodies a truly French approach to modern, prestige vehicles, far removed from passing trends and fashions. The Furtive-eGT is 4.46 m long with very short front and rear overhangs. The design is elegant and dynamic, while placing the emphasis squarely on aerodynamics. A car of pure, clean lines, the Furtive-eGT stands out from the crowd with distinctive features, such as the double-bubble roof, headlight signature and rear wings to optimise downforce.
2. Siemens electric motors
The Furtive-eGT is driven by two latest-generation electric motors from Siemens Inside e-Car. Installed centrally on an aluminium cradle at the rear, and linked by the three-speed gearbox with seamless torque delivery, they drive the rear wheels of the Furtive-eGT (rear-wheel drive). From the driver’s standpoint, the two motors act as one even though the electronic controls allow them to operate separately. The two motors are liquid-cooled to maintain performance levels in all conditions of use.
These electric motors are among the most compact on the market. They each develop 148 kW – or 296 kW overall – a level of power equivalent to 402 bhp, for an outstanding level of efficiency. Maximum power of between 5,000 and 10,000 rpm is available in one-tenth of a second, with constant torque of 516 N.m (258 N.m x 2) between 0 and 5,000 rpm.
These motors, developed specially by Siemens for the needs of the Furtive-eGT, each weigh 51 kg. Viewed against their individual rated power of 148 kW, this gives them energy density of 2.901 kW/kg, an excellent figure, with efficiency close to 98%. Two inverters, also developed specially for the Furtive-eGT, distribute electric power by converting the direct current from the Saft battery into alternating current. The inverters drive the motors in two modes, based on torque or engine speed, modifying amplitude and frequency as necessary. The “supervisor” control electronics were developed internally by Exagon.
Accelerating from 0 to 100 kph in just 3.5 seconds, the Furtive-eGT ranks among the best supercars on the market. The response time between pedal depression and the delivery of power is just one-tenth of a second. The Siemens motors use this power for a level of acceleration never before enjoyed by drivers. The top speed is limited electronically to 250 kph.
On deceleration, the magnetic field of the electric motors contributes to the car’s exceptional braking properties, with each motor acting as a generator to recharge the batteries and thus increase vehicle range. Together, the motor brakes and callipers developed for the Furtive-eGT by BERINGER develop up to 1.2 G during the braking phase, slashing stopping distances and making this one of the world’s best braking systems.
Maintenance and environmental protection
The Siemens Inside e-Car electric motors have few moving parts and deliver a level of reliability far beyond that of combustion engines. No upkeep is required before 150,000 kilometres, which makes them virtually maintenance free. They are silent by definition, emitting no carbon or NOx.
3. Saft batteries
The Furtive-eGT is equipped with batteries made by Saft, world leader in lithium-ion batteries. The company holds market share of 80% in the aerospace industry as well as in the defence industry and in Formula 1, reflecting the quality and advanced technology of the components used, and the high safety standards in all circumstances. These latest-generation batteries have a capacity of 53 kWh and a rated voltage of 360 V. They weigh 480 kg overall.
Exagon Motors turned the constraint of battery weight into an advantage. The architecture of the carbon body made it possible to install the batteries in the floor of the Furtive-eGT. This lowers the centre of gravity (110 mm lower than on a conventional GT) to virtually eliminate roll on cornering, for exceptional ride and handling. This feature makes a key contribution to roadholding and thus to the driving sensations delivered by the Furtive-eGT.
With its Saft batteries, the Furtive-eGT no doubt has a greater range in all-electric mode than any other high-performance electric vehicle:
• 360 km over an urban cycle (ECE15 standard).
• 310 km over a combined cycle (NEDC standard).
• 287 km over a motorway cycle (EUDC standard).
Service life and recyclability
Saft batteries are highly recyclable. After 3,000 cycles, being used virtually every day over a period of ten years, they still have at least 80% of their energy capacity. Moreover, they have no memory effect.
Optional range extender
The Furtive-eGT ships with an optional range extender. This takes the form of a small combustion engine of low cubic capacity that recharges the batteries when they reach their range limits. It does not drive the wheels, it acts solely as a generator. Pollutant emissions are therefore very low, since it is optimised to run at constant speed. The range extender increases the overall range of the Furtive-eGT to 807 km with 25 l of fuel over a standard ECE15 cycle, or 734 km with 25l of fuel over a standard combined cycle.
4. Transmission system and gearbox
The Furtive-eGT features an exclusive three-speed gearbox with seamless torque delivery. Gear changing is smooth and immediate, with no loss of power.
On each gear change, one of the two motors continues to transmit power to the wheels. This process avoids any break in torque to maintain power in all circumstances. Furthermore, the motors function continuously within their optimum range of power and efficiency, enabling the vehicle to take full advantage of their power and to increase energy efficiency.
Technology developed by Exagon Motors
The engineers of Exagon Motors developed this gearbox specially for an electric motor. It is therefore able to accommodate the instant torque delivery. Unlike other supercars, fitted with sequential gearboxes, the Furtive-eGT runs no risk of the clutch breaking in the event of violent acceleration. It is designed for use without a clutch, either in manual mode with the steering-wheel mounted paddles or in automatic mode. For reverse gear, the rotational direction of the motors is inverted.
5. Carbon chassis/body
The monocoque body of the Furtive-eGT is made entirely of a carbon fibre/honeycomb structure based on Formula 1 technology. This exclusive feature is shared by very few of the world’s supercars, since only seven other exceptional sports vehicles feature the same level of technical sophistication, and all are driven by combustion engines. The carbon body of the Furtive-eGT weighs just 124 kg overall. Torsional stiffness is exceptional, contributing to the lateral grip and neutral behaviour of the Furtive-eGT.
The body directly supports the front half-axles, optimising both weight and overall stiffness. At the rear, a cast aluminium structure carries the powertrain and rear half-axles. A low centre of gravity for an exemplary ride
The carbon body was designed to house the batteries in its structural floor. The battery position gives the car a low centre of gravity, around 110 mm lower than on a conventional supercar, positioned centrally with respect to the wheels. This strategic battery layout ensures stable ride and handling.
It also optimises comfort, significantly reducing roll on cornering, and limiting weight transfer – and thus pitch – on braking.
6. Running gear
The running gear of the Furtive-eGT was developed in partnership with Michelin, a group with globally recognised expertise. Over the past two years, engineers from Exagon Motors and Michelin have worked in close cooperation, carrying out extensive tests on the Michelin tracks in Ladoux, near Clermont-Ferrand. The result strikes the ideal balance between roadholding and comfort, reflecting the advanced performance of the Furtive-eGT and the specific constraints of electric drivetrains. Michelin’s expertise was combined with that of Exagon in developing running gear and designing motorsports vehicles.
Double wishbone suspension
The Furtive-eGT features double wishbone suspension at both front and rear. This is currently the best solution for optimising tyre operation and maintaining an ideal position on the road in all circumstances. The half-axles, made using the Cobapress process, are mounted directly on the carbon body at the front and on an aluminium cradle at the rear. Given the immediate availability of electric power (and torque from 0 to 5,000 rpm), the suspension and tyres had to be specially designed to accommodate this level of torque with running gear that would be ideal in all circumstances. The suspension layout and damping control optimise vehicle behaviour without any sort of management system. Special emphasis was placed on making the suspension comfortable, particularly on bumpy roads, a feature that is not generally the case on cars delivering this level of performance.
Exclusive tyres and specially designed brakes
The Furtive-eGT is equipped with Michelin Super Sport, 245/35 ZR 20 tyres at the front and 305/30 ZR 20 at the rear. They were specially developed to accommodate the acceleration of electric motors. Rolling resistance was decreased and grip improved for even higher standards of energy efficiency. The brake callipers, which have six pistons at the front and four at the rear, were developed for the Furtive-eGT by Beringer, a French company with renowned expertise in the aerospace industry. The vented discs – 380 mm at the front and 360 mm at the rear – are made of steel and designed to optimise braking in all circumstances, with deceleration of 1.2 G.
7. A personalised driving experience
The Furtive-eGT is equally at ease in both day-to-day and sport driving. To meet a full range of driver requirements, depending on vehicle use, the engineers at Exagon Motors developed four operating modes for a personalised driving experience: Standard, Eco, City and Sport.
In Sport mode, the emphasis is squarely on performance and sport driving, with specific accelerator response, acceleration control and motor speed for gear changing.
In Standard mode the motors function normally, delivering full power and optimising motor speed for gear changing, to improve efficiency and focus on driveability.
In Eco mode, the power of the motors and peripheral electricity-consuming functions are limited in order to place greater emphasis on range and to make the Furtive-eGT easier to handle by an uninitiated driver.
In City mode, vehicle operation is optimised for low speeds, with the emphasis on smooth driving. The air in the cabin is recycled automatically to reduce the nuisance caused by exhaust gases from other vehicles.
An adaptive digital dashboard
Depending on the mode selected, the 12-inch digital display on the dashboard behind the steering wheel changes configuration to show pertinent information to the driver:
• Standard mode: vehicle speed is shown on the large central dial, with the rpm of the two motors on the left and the kW transmitted by these motors on the right. GPS navigation data can be displayed on the right-hand dial, superimposed on kW data. Both are legible.
• Eco and City mode: the kW used are shown in the large central dial for eco-driving (force required), the speed is displayed on the right and the rpm of both motors on the left.
• Sport mode: rpm are displayed on the central dial with a digital speed display, G force measured on the left and kW used on the right.
8. Design and aerodynamics
Although the Furtive-eGT is a sports car with an electric drivetrain, it is first and foremost a grand tourer. A fact that is clearly visible in its taut, elegant design lines.
At the front end, the headlights of the Furtive-eGT use full-LED technology for all lighting and signalling functions. This makes for comfortable night driving as well as saving energy. At the same time, the miniature LEDs enabled designers at Exagon Motors to give the Furtive-eGT its piercing gaze.
At the rear, the boot line rises up from the wings to meet the double bubble and side wings. While the extractor is the visible part of the aerodynamic flat bottom design of the Furtive-eGT.
9. Infotainment & multimedia
The Furtive-eGT is equipped with a multimedia infotainment system developed in partnership with Nokia. It includes a 9-inch central capacitive touch screen with swipe and zoom functions. The system comes with a SIM card enabling a continuous dialogue with the manufacturer, particularly for technical self-diagnosis data, emergency calls or weather bulletins. It is also equipped with a USB connection, an auxiliary socket and the Bluetooth streaming function.
Made-to-measure applications on request
Using the OS and multimedia interface of the Furtive-eGT, Exagon Motors is able to develop special applications to be downloaded directly to the car, a first in the automotive world. For example, if the owner of a Furtive-eGT is interested in modern art museums, he or she can request an application grouping all relevant information (contact details, opening hours, current exhibitions, navigation, etc.), which will be specially developed and sent directly to the car’s infotainment system. These personalised applications can be developed when the order is placed or installed throughout the vehicle’s service life. This is an open-ended system able to receive the latest technological innovations in real time.
An exclusive partnership with Focal
For the acoustics of the Furtive-eGT, Exagon Motors opted for excellence by teaming up with Focal, France’s leading acoustic designer and manufacturer. Over more than 30 years, Focal has developed globally recognised expertise in the high-tech field of transducers. By working with the manufacturer of the world’s best audio loudspeakers, Exagon Motors is out to give Furtive-eGT drivers access to the superlative Focal sound that is so appreciated by music-lovers.
Exclusive e-Motion Sound Concept
For the Furtive-eGT, Focal developed a system called eMSC or Exclusive e-Motion Sound Concept. This system uses exclusive technologies and rare materials, carefully crafted in the French workshops of Focal, for enhanced listening pleasure. But the science of onboard acoustics does not stop there. Layout and volumes have also been optimised. Nothing has been left to chance: positioning, vibration behaviour and volumes were carefully calculated to get the best out of the cabin of the Furtive-eGT.
Two acoustic options are available for the Furtive-eGT, based on the best technology used by Focal for its flagship products.
• “Harmony”, the first level, features ten-channel acoustic architecture based on Kevlar membrane technology. With this option, Focal has developed a dynamic, steady, comfortable system that accompanies listeners whenever they want to step up the pace.
• “Quintessence”, the second level, will delight music-lovers. It uses exclusive technologies from the Utopia range to further optimise every aspect of the listening experience. The W membrane (glass/glass) restores the full impact and velocity of bass tones, while the famous tweeter made of Beryllium, a precious material perfectly suited to the needs of acousticians, achieves a high-precision treble for a result that will delight music lovers.
10. Customisation programme
The quest for technological excellence is associated with the idea of made-to-measure design that was widespread in the automotive industry of the 1930s. Luc Marchetti wanted to recreate this mindset, based on an approach that gave pre-war French vehicle manufacturers international renown. At the time, in the prestige vehicle industry, it was common for customers to order a chassis and engine from a leading manufacturer and then to have the bodywork and interior designed to measure by a renowned coachmaker. This approach led to the creation of real automotive treasures, unique vehicles that have since gained the status of works of art.
The ambition of the Furtive-eGT is to bring customers a degree of customisation rarely achieved to date. This is where the idea of automotive craftsmanship or jewel-making comes in. Luc Marchetti explains:
“France is recognised the world over for its virtuosity in high-end manufacturing. We have a unique age-old expertise, with both suppliers and craftsmen. Strangely, this inexhaustible pool of talent has never, or rarely, been tapped by the automotive industry. A fact that is no doubt linked to the specifics of volume production. The Furtive does away with these constraints, since our production is exclusive (planned at around one hundred vehicles per year) and each model will be assembled by hand. This means that for the first time, we can deliver truly exceptional made-to-measure design. Each customer can be sure of owning not just a unique vehicle but a real work of art created specially for him or her. Like an interior decorator who seeks to understand exactly what you want before bringing in the best craftsmen to decorate your home, Exagon Motors will study each customer’s requirements individually and submit new ideas, some of which may be penned by leading designers. The most important aspect is to create a long-term relationship of trust. The time devoted by the customer to the design of his or her Furtive-eGT should be an enjoyable, even magical, experience.”
11. Distribution, service, maintenance and warranty
Regional ambassadors will manage distribution of the Furtive-eGT and represent the Exagon brand.
The Furtive-eGT ships with a two-year warranty. This warranty may be extended to five years if all maintenance, top-ups and servicing are carried out exclusively by Exagon Motors. To this end, the brand is putting in place an exclusive automotive concierge service. This service will function on a 24/7 basis to satisfy the needs and requirements expressed.
Maintenance operations and upgrades (IT set-up, upgrades, braking, routine servicing) may be carried out directly at the customer’s home.