The convertible’s three-piece hardtop provides open-air freedom with the top down through the operation of a convenient single switch. Constructed primarily of lightweight aluminum, the hardtop also provides surprising storage space but with low noise and increased security not typically found in soft-top convertibles. In addition, the top completely retracts with no elements remaining in view.
The four-link roof assembly, also made of aluminum for a lightweight design, provides smooth, even movement. Engineered to operate in an easy, efficient manner, each component is motor driven with detection switches, allowing the control unit to know their exact position at all times. In addition to the two main roof panels being constructed of light-weight aluminum, the back window’s reinforced glass construction also lends itself to reduced weight. Weather-strip changes in areas around the doors and windows ensure tight seals.
A roof-speed brake-control system decreases the roof speed especially as it approaches the end of the closing operation in either direction, ensuring an elegant and quiet movement. On models equipped with available Intuitive Park Assist (IPA), sonar sensors in the rear bumper will stop the movement of the luggage door at the start of operation if it detects an obstacle will interfere. Also, a visual warning will appear on the instrument panel if a detected obstacle may soon interfere with top operation.
When the IS convertible’s top is opened or closed, the power windows will automatically lower if in the closed position, and raise back up when the operating switch is held. Also, when the top is up, the door windows automatically lower 15 mm when the door opens, and then raise back into a fully closed position when the door closes. This ensures the doors’ clean open/close function while also maintaining a tight seal around the glass. The aluminum hardtop features an automatic front lock assembly that provides the interior security not found in soft-top convertibles. When the top is stowed in the down position in the rear of the IS convertible, the lock assembly is engaged to keep the panel in a fixed, stable position.
The IS convertible’s body structure has excellent rigidity and strength, achieved by effective structural changes and additions to the existing IS sedan platform. Areas that received modifications or additions include the rocker area; A and B pillar under structure; side collision crossmember, and upper and rear-floor crossmembers. In addition, underfloor braces were added both in the front and the rear. Additional bracing was implemented to help provide excellent handling control, ride comfort and body durability while also minimizing weight gain.
The transformation to a convertible also required reevaluation of noise, vibration and harshness (NVH) characteristics in order to meet Lexus standards. All body and chassis revisions went through extensive testing to ensure that the IS 250C and IS 350C have nearly identical NVH characteristics to the IS sedans. High-rigidity damping materials and asphalt sheets were added to help minimize vibration effects. Redesigned rear-suspension-mount bushings help reduce noise and vibration associated with the changes in body characteristics from a sedan to a convertible. Additional sound absorption and insulation materials were optimally positioned to create a quiet, comfortable cabin.
The IS convertible features two wheels. Standard 17-inch wheels utilize two multi-layered five-spoke patterns for a contemporary 10-spoke design with a clean liquid-graphite finish. Optional 18-inch wheels with all-season tires have an athletic five-spoke design with a liquid-graphite finish. Both feature the tire pressure monitor system found on the sedan models.
The IS 250C and IS 350C provide a consistent blend of driving performance and comfort in either convertible or coupe configuration. They share common double-wishbone front and multi-link rear suspension systems with the IS sport sedan models.
Engineers tuned and optimized specific features for the convertible including the double-wishbone front suspension for handling control and ride comfort; the torsional rigidity of the suspension bushings, the spring constant on the coil springs, and the shock absorber damping force; the stabilizer shape and the Electric Power Steering (EPS) gear ratio for control; the suspension bushings, coil springs and shock-damping force of the multi-link rear suspension; and a lowered rear-suspension tower with enhanced rigidity to help provide rear control, linear yaw response and improved trunk space.
Standard Vehicle Dynamics Integrated Management System (VDIM) governs all of the vehicle’s dynamic handling systems – the Anti-lock Braking System (ABS), Brake Assist (BA), Vehicle Stability Control (VSC) and Traction Control (TRAC) – employing them collectively and seamlessly to make corrections while helping provide higher dynamic capability. VDIM also interfaces with the electronic throttle control system. The IS convertible features large, ventilated four-wheel disc brakes with ABS, Electronic Brake force Distribution (EBD) and BA. The IS 350C is equipped with 13.2-inch front and 12.2-inch rear rotors with aluminum four-piston front calipers to aid in heat dissipation and stopping power and reduce unsprung weight. The IS 250C has 11.7-inch front and 12.2-inch rear rotors.
Lexus Safety and Security
Passive-safety technology begins with a number of body-structure changes integrated in the IS 250C and IS 350C to help augment strength and torsional rigidity. Seatbelt pre-tensioners and force limiters are used for the front seats, while the rear seats adopt emergency locking retractor seatbelts with an automatic locking retractor.
In addition to the dual-front airbags, the Lexus Supplemental Restraint System (SRS) for the IS convertible includes front-seat-mounted head and torso side airbags, and knee airbags for both the driver and the front passenger. The front-passenger airbag features two chambers, creating an indentation in the center impact area.
The IS convertible emphasizes easy access and rear-seat comfort. In addition to front doors that are 11.8 inches longer than the IS sedans, two convenient fold-forward lock-release levers are standard on both sides of the front passenger seats, making it easier to operate from any location inside the vehicle. The passenger seat features a power slide button on the top of the seatback to ease rear seat ingress/egress. An available automatic one-touch, easy-entry power-seat mechanism provides even easier egress and ingress through quick-acting, front-seat fold-and-slide activation. The two passenger doors also have three open-stopping positions (rather than the normal two) to add convenience in various parking situations. The IS convertible also is equipped with a standard power tilt and telescoping steering column to help the driver quickly get into a comfortable position.
The IS convertible’s air conditioning system automatically adjusts for the outside temperature when the top is lowered, improving interior temperature consistency and comfort. The system adjusts the air outlets, temperature and air flow exiting the outlets. The airflow volume adjusts to outside temperature and vehicle speed, while the temperature control adjusts to outside temperature, amount of sunlight and vehicle speed. The system also includes a pollen filter and variable-control compressor.
The standard SmartAccess keyless entry and push-button-start/stop allows the driver to keep the access key fob in a pocket or purse. The standard HomeLink® programmable garage door opener also operates home security devices and other systems.
Models equipped with an automatic transmission have standard Hill-start Assist Control (HAC). HAC helps prevent the vehicle from moving backward when the driver moves their foot from brake pedal to the accelerator.
The standard Lexus Premium Audio System features a six-disc, in-dash CD changer, eight speakers, integrated SiriusXM Satellite Radio receiver (complimentary 90-day trial subscription included), Bluetooth® hands free phone capability and music streaming, and USB/iPod® connectivity. An equalizer system maintains the same acoustic field when the top is either open or closed, compensating for the natural loss of bass sounds when open. When connected to the USB port, the iPod can be controlled through the audio system or steering wheel controls, while information such as names for the artist, track and album is displayed on the headunit or navigation screen.
Lexus’ Hard-Disk Drive (HDD) navigation system is available on the IS convertible and is complete with a seven-inch VGA touch-screen, and back-up camera. The navigation system also includes Voice Command casual-language voice recognition system. With Voice Command users avoid having to speak commands in a specific order. The Voice Command system also works to control many functions of the audio system, heating and air conditioning, and the navigation system.
Like all Lexus models, the IS convertible offers a Mark Levinson® Premium Surround Sound Audio system which is available in conjunction with the optional navigation system. This 12-speaker audio system features discrete 5.1 multi-channel playback with 5.1-channel speaker architecture. Its nine amplifier channels provide 270 watts total output at 0.1 percent total harmonic distortion (THD). From 20-20,000Hz, the Mark Levinson system plays conventional CDs and specially encoded DVD audio and DVD video discs, plus MP3/WMA-formatted CD-R/RW and DVD-R/RW. DVD movies can be viewed on the optional navigation system's color touch screen when the parking brake is engaged.
Optional Bi-Xenon HID headlamps with LED daytime running lamps (DRLs) are also available. The HID headlamps produce a whiter light and have a longer reach and wider distribution than conventional headlamps to help drivers see more clearly. LED DRLs help make the vehicle more visible.
The optional Intuitive Park Assist (IPA) system uses ultrasonic sensors to detect objects close to the car's front and rear bumpers, alerting the driver and showing distance to objects in the multi-information display within the speedometer. When equipped with the optional navigation system, the area behind the vehicle is shown in greater detail on the navigation screen via the backup camera.
The optional Pre-Collision System (PCS) is packaged with Dynamic Radar Cruise Control, which uses millimeter-wave radar to measure and help maintain a set distance from a vehicle traveling ahead. PCS relies on the radar sensor to detect obstacles in front of the car, and a PCS computer with sensor inputs from vehicle speed, steering angle and yaw rate is designed to determine whether a collision is unavoidable. In such a situation, PCS alerts the driver via sound and visual warnings while preemptively retracting front seat belts and pre-initializing BA so that increased braking will be applied the instant the driver depresses the pedal.
The IS convertible also offers a telematics system, Lexus Enform® with Safety Connect®, available by subscription. Safety Connect is standard on all vehicles while Lexus Enform with Safety Connect is on all vehicles equipped with the optional Navigation system. Complimentary one-year trial subscriptions are included on all purchases of new Lexus vehicles equipped with these features. The Lexus Enform and the Safety Connect response centers operate 24 hours a day, 7 days a week—every day of the year.
Lexus Enform vehicles are factory ready for subscriptions to a variety of innovative SiriusXM services including NavTraffic, NavWeather, Sports, and Stocks. SiriusXM services offer complimentary 90-day trial subscriptions and require separate SiriusXM subscriptions.
F Sport Performance Accessories Available for IS Convertible
The IS convertible F Sport Performance Accessories include performance enhancing parts such as 19-inch forged alloy wheels, brake upgrades, suspension systems, air intake, exhaust systems and more.
F Sport Performance Accessories by Lexus U.S.A. are engineered by Toyota Racing Development (TRD). When installed by an authorized dealer, the accessories are fully warranted for 12 months or for the balance of the new car warranty, whichever is greater.
The IS 250C and IS 350C’s exterior design has its lineage in the IS sedan but possesses its own dynamic styling, including unique characteristics when interchanging between convertible and coupe configurations. With the exception of the hood, all other body panels have been specifically designed to blend seamlessly with the three-panel folding roof.
The convex shoulder lines distinguish the convertible’s profile, while the top-up configuration provides a sweeping cabin silhouette. With the top down, the belt-line draws up around the rear deck lid, providing a muscular look.
In the front, hood lines flow into a unique chrome grille shape, then continue down into an air inlet before flowing outward past the more distinctive elliptical fog lamp design.
The rear view features a clean, continuous design, with flowing bumper corners and a strong bumper shape that flows inward towards the exhaust. The combination taillamp clusters feature LED lights and two distinct horizontal lines that emphasize breadth, while the LED brake light integrated within the standard rear spoiler imparts a sporty impression.
The IS convertible has a best-in-class 0.29 drag coefficient (Cd). This is accomplished with the help of underbody covers below the engine (with aerodynamic steps), the full floor, and fuel-tank covers, as well as a rear-floor diffuser with vertical fin and airfoil. Other areas that contribute to the low Cd include the design shape of the outer mirrors, high-mount stop lamps, and the rear taillamps. Fender fairings before the front and rear tires reduce airflow into the wheel house, improving aero characteristics and reducing air turbulence.