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New Lexus IS 250C

On sale throughout Europe in the summer of 2009, the new Lexus IS 250C combines the award winning design of the IS compact sedan range with outstanding open-top engineering ingenuity.
The IS 250C is a unique fusion of top-down driving pleasure and uncompromised dynamic performance. Reflecting the company?´s legendary quality and attention to detail in every aspect of its construction, the new Lexus has been rigorously engineered to demonstrate equally outstanding aerodynamic, torsional rigidity, NVH and safety characteristics in both coupe and convertible configurations.
Its lightweight folding roof structure boasts the world?´s fastest three-part roof opening and closing time of just 20 seconds and, thanks to the remarkably compact packaging of its folding mechanism, awards the IS 250C class-leading boot space, generous rear seat access and spacious rear passenger accommodation.
Sharing the IS 250?´s 153kW/208DIN hp, 2.5 litre V6 powerplant and 6-speed automatic transmission with manual paddle shift override, the new Lexus coupe/convertible has been styled to offer minimal wind turbulence when driving with the hard top stowed. Extensive revisions to body structure and suspension componentry equip the IS 250C with the torsional stiffness necessary to promote the ride comfort appropriate to every Lexus and, in coupe guise, offer class-leading Noise, Vibration and Harshness characteristics.
The new coupe/convertible is the third addition to the IS model range, joining petrol and diesel engined versions of the IS sedan, and the ultra-high performance, 5.0 litre V8 powered IS F, which introduces the Lexus F-Marque designation to the premium automotive segment for the first time.

Exterior Design
Building on the elegant proportions, sweeping sculptural lines and powerful contrasts in convex and concave surfacing which identify the IS sedan range as the latest realisation of Lexus ground-breaking L-finesse design philosophy, the new IS 250C combines the muscular grace of a dynamic, sporting coupe with the open-topped elegance of a stylish, comfortable and superbly refined convertible.
Offering a unique style which differentiates it from conventional convertibles, only the IS 250C?´s bonnet, headlamps, door handles and mirrors are common to the IS sedan. All other body panels have been redesigned to harmonise perfectly with the integration of the new coupe/convertible?´s three-part, aluminium folding roof.
The front overhang of the IS 250C is increased by 15mm over the sedan for improved top-down aerodynamic efficiency, and a new fog lamp design is integrated within the deep front air dam. In profile the coupe/convertible?´s powerful, sporting stance is characterised by elegant, muscular coachwork below a pronounced, rising beltline which kicks up towards the rear. The steeply raked windscreen flows seamlessly into the smooth, clean, aerodynamic arc of a roofline which penetrates the broad expanse of the boot surface via a crisp, elegant C pillar design incorporated within the folding roof structure. In coupe guise, the cabin tapers elegantly to the rear, allowing for a fluid roofline transition from C pillar to luggage compartment. To the rear, the IS 250C features new combination tail lamp clusters with instantly recognisable, linear LED illumination, and a highmounted LED stop light integrated within the upper boot lip.
With the hard top stowed, the IS 250C presents a seamless, elegant profile punctuated only by the integral roll-over hoops behind the rear seat headrests, reinforcing the full-length sweep of the rising beltline and the convertible?´s broad, purposeful rear stance. No roof mechanism elements remain in view or project above the vehicle?´s tapered waistline; the whole being entirely concealed beneath the broad, sweeping boot surface and adjacent, flush-fitting parcel shelf.

Interior Design and Comfort
Sharing the IS 250’s 153kW/208DIN hp, 2.5 litre ultra-smooth V6 powerplant and 6-speed automatic transmission, the new Lexus convertible has been styled to offer minimal wind turbulence when driving with the hard top stowed. The enhanced torsional stiffness of the IS 250C design promotes ride comfort appropriate to the marque and, in coupe configuration, reduced noise, vibration and harshness (NVH) characteristics on a par with those of the IS sedan
The IS 250C shares the sedan?´s high levels of interior luxury and practical innovation, with several bespoke technical revisions designed to ensure the effective operation of the vehicle?´s on-board comfort and entertainment systems when in convertible configuration.
Sporting, low profile, heated and ventilated front seats feature a newly developed, arched frame with integral seatbelt guide, and offer exceptional open-topped driving comfort through the addition of shoulder height heating pads, an increased heater capacity and increased ventilation airflow.
Set 30mm further inboard than those of the IS sedan to optimise headroom and divided by a practical centre console with built-in cupholders, the two, full-sized rear seats benefit from the revised, more slender front seat profile to offer ample legroom, with a class-leading 542mm from the rear H point to the front seatback.
Improved by a wide-aperture door 300mm longer than that of the IS sedan, rear seat access has been simplified through a onetouch walk-in button which offers high-speed, automatic front seat fold-and-slide activation for the ultimate in rear passenger convenience.
The IS 250C?´s rear overhang has been increased by 50mm over the sedan, which combines with the exceptionally compact packaging of the folding roof to generate a significant increase in luggage space. Offering a boot luggage capacity of 583 litres with the hard top in place and 235 litres with the roof down, the new Lexus is the only convertible in its class to accommodate a 9 golf bag with the hard top stowed and the luggage cover in place.
The instrument panel and surrounding components, as well as the steering wheel, are shared with the IS sedan range. However, the driver?´s instrument binnacle has been extensively revised to increase open-topped motoring visibly. The dial colour has been changed, LED contrast increased, and the glass transmissivity reduced from 30% to 20%. The dial needle shape has been revised and the dials themselves feature metal tone ring surrounds, whilst the central, multi-display screen benefits from a hardtop operation status indicator. In addition the rear view mirror mount has been strengthened and shortened to minimise shake. The climate control system has been specially configured for top-down motoring with the addition of a speed sensitive control which automatically increases air flow in roof-open mode, and further increases airflow according to vehicle speed. The centre console audio and navigation LCD touch screen has been improved to include a redesigned set-up screen and added audio system screen tabs. Both the standard 8 speaker, 246 Watt premium sound system and the 12 speaker, 365 Watt Mark Levinson Premium Surround System feature equaliser tuning to provide consistent audio quality whether the hard top is up or down, automatically adapting to the natural loss of bass when the roof is stowed.
The two systems also offer both USB and audio jack plug connectivity for the fully controlled use of portable music players such as iPods, and Bluetooth mobile phone connectivity with an audio/video streaming function. Benefiting from the Lexus Navigation System?´s HDD hard drive, the Mark Levinson Premium Surround System also features a Sound Library facility. A new Lexus Navigation System benefits from a powerful, 40Gb HDD capacity, making it one of the fastest, most accurate systems on the market. It covers the whole of Europe, and includes the traffic information infrastructure of each country. The new system features upgraded voice recognition, with four additional languages including Russian, and a new menu that can be operated in 14 languages including cyrillic characters.

Three-Part Folding Roof
Constructed entirely in lightweight aluminium, the new IS 250C’s folding roof structure offers an unparalleled level of smooth, seamless and silent operation, and boasts the fastest three-part roof opening and closing time of just 20 seconds. Through the remarkably compact packaging of its roof mechanism, the IS 250C offers class-leading boot space, generous rear seat access and spacious rear passenger accommodation.
Constructed entirely in lightweight aluminium, the new IS 250C?´s folding roof structure boats the world?´s fastest three-part roof opening and closing time of just 20 seconds.
Reflecting all the Lexus quality and attention to detail gained from the company?´s experience of its SC convertible, the folding hard top employs 13 motors and 33 sensors to offer an unparalleled level of smooth, seamless and silent operation. The entire roof headlining is trimmed in fabric for optimum quality and acoustic comfort, and painstaking attention to the detailing of all seals further aids acoustic comfort whilst ensuring the absence of leaks due to rain, car washes or even high pressure cleaning jets.
Activated via a one-touch, dashboard-mounted button, the ultra-quiet operating mechanism features a unique roof brake component which slows the closing of the hard top as it approaches the windscreen head. This ensures that, unlike many mechanisms in which the weight of the roof structure causes an increase in operating speed just before the point of closure, the IS 250C?´s hard top descends smoothly into place.
Because the hard top roof folding operation extends the upper boot lip 250mm beyond the rear bumper, the roof folding system incorporates a clearance sonar safety system integrated within the IS 250C?´s rear bumper to remove the risk of damage to system components during operation. If the system identifies obstacles between 350mm and 450mm from the rear bumper, it will remain operational but issue a proximity warning to the driver. If an obstacle is detected less than 350mm from the rear bumper, the system automatically becomes inoperable, and the appropriate warning is issued to the driver. Both proximity warnings and advisories from the clearance sonar and a hard top operation status indicator appear on the multidisplay screen within the driver?´s instrument binnacle.

Aerodynamics and Wind Stream Management
On sale in the summer of 2009, the new IS 250C has been enginereed with the aim of achieving a top Euro NCAP safety rating.
Benefiting from a steeply raked windscreen, ultra-smooth cabin profile and aerodynamically efficient, duck-tail rear styling featuring airkick effect rear tail lamp clusters, the new coupe/convertible has been designed to combine the lowest possible drag coefficient with minimal wind turbulence affecting the open cabin. Hard top in place, the IS 250C?´s drag coefficient of just 0.29 compares extremely favourably with the sedan?´s exceptional 0.27Cd rating.
Lexus design engineers have focused particular attention on reducing wind turbulence and generating the most comfortable air flow characteristics for occupants with the hard top lowered. The angle of the front windscreen allied to the painstakingly detailed windscreen head design are major contributors to the achievement of exceptionally low wind turbulence around the face, shoulders and thighs of occupants, even without the optional rear seat mounted wind deflector in place.
Key to the IS 250C?´s aerodynamic performance is a comprehensive array of underbody covers matched to newly designed underbracing which ensures maximum torsional rigidity for the new convertible. The covers include a front spoiler, an engine undercover with aerodynamic steps to promote the Venturi effect, a transmission undercover, front and rear wheel spats, full floor and fuel tank covers, a rear suspension cover and a rear floor diffuser with vertical fin and airfoil.
Generated by the Venturi effect at the front of the vehicle, a flat middle section and a rear diffuser effect astern, a smooth, fast underbody airflow promotes reduced lift and aerodynamic drag, significantly enhancing high speed vehicle stability.

High Rigidity, High Strength Bodyshell
Numerous body structure changes have been incorporated in the IS 250C to enhance collision strength, roll-over protection and torsional rigidity, minimising cowl shake and optimising chassis controllability.
Torsional rigidity has been optimised through comprehensive underfloor bracing, which includes front and rear V-shaped and torque box braces, a front underfloor trapezoidal brace and a rear suspension brace.
High tensile strength sheet steel front (100kg class), as well as upper and floor level rear cross-members have been incorporated, whilst gussets joining the upper part of the B pillar to the upper rear cross-member contain body deformation in the event of a side impact. Furthermore, a sub-latch mounted on the trailing edge of the door impact beam transmits side impact energy to the lower B pillar, further enhancing safety.
The A pillar is constructed from ultra-high tensile strength sheet steel (150kg) class, the lower A pillar incorporates a combined centre plate and boot plate structure, and the lower B pillar has a plate added to suppress surface buckling due to the height difference between the upper surface of the rocker panel and the strengthened rear floor cross member. The rocker panel itself has an enlarged cross-section, 55mm taller and 29mm wider than that of the sedan, for improved torsional and flexural rigidity as well as enhanced collision strength.

Ride and Handling
The new IS 250C employs the proven double wishbone front and multi-link rear suspension format of the IS sedan range to offer a sporting, agile driving experience. However, significant chassis revisions have been incorporated to promote the greater ride comfort appropriate to a convertible, and ensure a consistent dynamic performance in both coupe and convertible guise. In the interests of optimum ride comfort, the front suspension coil springs and dampers have been fine tuned, the suspension bushing torsional stiffness reduced and the anti-roll bar shape optimised. The Electric Power Steering also benefits from a bespoke gear ratio for maximum vehicle controllability and stability.
Rear suspension revisions include coil spring and damper fine tuning for improved ride comfort, high capacity suspension member rubber mounts for reduced vibration, and reductions in suspension bushing torsional rigidity to further improve ride comfort through a smooth suspension movement with minimal alignment change. The rear toe-control arm has been redesigned, a performance ring added to the suspension tower, and the suspension upper support has been lowered to increase rigidity, increase luggage space and improve linear yaw response.

In conjunction with extensive temperature, vibration and shaking tests, these comprehensive bodyshell and chassis revisions have been implemented with the express aim of ensuring that, in coupe configuration, the IS 250C demonstrates class-leading Noise, Vibration and Harshness characteristics.
Comprehensive underfloor bracing allied to the use of high tensile strength sheet steel cross-bracing promotes a high rigidity body structure to eliminate body and cowl shake. Front and rear suspension fine tuning and mounting revisions reduce vibration at idle and minimise both the transmission of noise and vibrations from the road surface. And the effective allocation of sound insulation, in particular within the rear partition, further minimises booming, road and engine noise.
The use of acoustic windscreen glass allied to painstakingly optimised roof, door and window panel seals awards the IS 250C class-leading low wind noise levels.

The IS 250C has been enginereed with the aim of achieving a top rating in both Euro and US NCAP crash testing, offering worldclass safety in either coupe or convertible configuration.
In keeping with the IS sedan range, the new Lexus coupe/convertible benefits from the highest content of sophisticated active and passive safety technology in the segment, including Lexus state-of-the-art Vehicle Dynamics Integrated Management (VDIM) incorporating open body specific VSC tuning for shorter stopping distances on split-friction road surfaces, a revised Pre-Crash Safety (PCS) system which supports the pre-crash seatbelt and pre-crash brake assist functions with pre-crash brake technology, and the world?´s first SRS twin-chamber passenger airbag.
Further improving the new Lexus safety credentials in open-topped mode, the IS 250C is equipped with a new design of enlarged side airbag which provides head protection in the event of side impact. The coupe/convertible bodyshell has also been equipped with additional, energy absorbing side impact pads for both front and rear seat occupants.

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