- New laser screw and adhesive body bonding techniques for a substantial increase in overall body rigidity
- Use of hot stamped and high-tensile steel sheets, and aluminium for a 10 kg reduction in bodyshell weight
- Revised front suspension with a 20% increase in roll rigidity, new multilink rear suspension for increased grip and stability
- New Electric Power Steering System for a lighter, smoother more accurate feel with greater feedback
- Newly Adopted Drive Mode Select -switchable optimization of economy, comfort, performance and handling characteristics
- Adaptive Variable Suspension (AVS) system available for fine tuning ride characteristics with a choice of NORMAL or SPORT S+ modes
The target of segment-leading driving enjoyment has been at the heart of the new IS development program, and -sacrificing none of the quietness and comfort inherent in any Lexus- every aspect of the new compact sedan’s driving dynamics has been painstakingly engineered to that end.
The new bodyshell is lighter, yet more rigid than its predecessor. The front suspension system has been revised, and an all new rear suspension system adopted, combining outstanding grip performance with excellent response to steering inputs. A new steering system offers a lighter, smoother, more accurate steering feel with enhanced response to inputs and greater feedback to the driver.
A new Drive Mode Select system features up to five switchable driving modes- ECO, SNOW, NORMAL, SPORT/SPORT S and SPORT S+ (the latter is optional on IS 350 F Sport models), to optimize the driver’s preferred combination of economy, comfort, performance and handling characteristics.
Lighter Bodyshell with Improved Rigidity
New, laser screw and adhesive body bonding techniques, along with additional spot welding, have substantially increased overall body rigidity. This not only enhances stability and body control, but also allows for a more comfortable ride with no detriment to handling agility.
The comprehensive use of body adhesives is a major factor in the optimization of the new IS’s handling. Rather than joining panels at points, as in spot welding, the body adhesive technique forms a bond along the entire surface of joined panels, maximising the rigidity of the joints. Over 25 metres of body adhesive has been used in the new IS, with a significant effect on the enhancement of body rigidity and improves the bodyshell’s vibration damping characteristics.
Adopted for the first time on the new LS, laser screw welding has been applied to the door openings and around the upper back panel. This new technique achieves a fine pitch not possible with spot welding, joining a larger panel area than traditional welding to better suppress cross-sectional deformation.
Handling stability and steering response are further improved through the adoption of a new rear subframe, cowl side braces which connect the front pillar and apron member, and underbody rigidity enhancement measures including a new radiator support and optimized bracing to the front, rear and transmission tunnel areas.
Weight reduction was a second important goal in the development of the new IS bodyshell. The use of hot stamped and high-tensile steel sheets for reinforcements and other critical components combines strength and structural simplification with a reduction in weight. This, allied to the use of aluminium in various locations including the bonnet, has made the new IS 10 kg lighter than its predecessor.
Revised Front Suspension and New Rear Multilink Suspension
The new IS combines a revised double wishbone front suspension system with a new multilink rear suspension similar to that of the latest generation Lexus GS. Both systems have been fine tuned to match the driving feel of the new Lexus, combining improved ride comfort with outstanding grip performance and excellent response to steering inputs.
The front suspension system features revisions to the upper support, hub and bearing, stabilizer link, bushing and bar, and the lower arm. The stabilizer layout has been revised and bar rigidity increased by 20% to reduce roll during cornering. Compensating for this increase in stabilizer rigidity, the coil spring rate has been lowered, enhancing ride comfort.
Roll rigidity distribution has been increased to help optimize steering response and stability during emergency maneuvers. In addition, the front lower arm No. 1 bushing rigidity has been doubled to enhance yaw response during steering.
The new multilink rear suspension features a separately located coil spring and shock absorber which increases shock absorber efficiency, enhancing ride comfort. This modified layout has increased the pitch between the suspension towers, increasing luggage space.
The multilink suspension has been substantially revised for installation in the new IS, with revisions to both upper and lower arms, the toe control arm, the upper support, shock absorber, carrier, hub bearing and stabilizer.
The characteristics of the bushing and shock absorber sliding parts have been optimized by adopting a lightweight, resin-free piston with sliding ring, achieving a 53% reduction in suspension friction. And locating the toe control arm at the back increases tire grip by some 15% when cornering, contributing to excellent stability.
New Electric Power Steering System
Steering feel and feedback is fundamental to an enjoyable driving experience, and the IS’s new Electric Power Steering (EPS) system benefits from a steering gearbox based on that of the new GS, incorporating a variety of tuning implementations.
With particular attention paid to a clear perception of the neutral steering position, the structure and rigidity of each gear box component has been revised to create a lighter, smoother, more accurate steering feel with enhanced response to input and greater feedback to the driver.
The stroke ratio of the power steering gear has been increased by some 8%, changing the rack stroke per pinion turn to 55.6 mm. The rigidity of the rack bushing has been increased to four times that of the current model, rack end bushing wear has been reduced, and the use of floating end bushings offers enhanced response to minor steering adjustments. Within the steering gearbox, pinion gear support rigidity has been increased and the ball screw structure has been modified to enhance the smoothness of motor torque transfer.
In conjunction with these comprehensive improvements, the EPS assist characteristics have also been optimized to further enhance the vehicle’s dynamic performance and steering feel.
Enhanced Braking Performance
The IS features a completely new brake system, designed to offer the quick response, smooth, linear effectiveness and controllability appropriate to a Lexus sports sedan.
The IS 250 is fitted with 296x28 mm ventilated front discs and 290x10 mm solid discs to the rear. IS 250 model rear brakes are equipped with newly developed lightweight aluminium alloy brake calipers. IS 350 feature 334x30 mm ventilated front discs, and 310x18 mm ventilated discs to the rear with the lightweight aluminium alloy rear brake calipers derived from the new GS.
The compact, lightweight master cylinder and stroke simulator have been designed using knowledge gleaned from the development of the LFA. Brake booster power has been optimized to enhance brake effectiveness and controllability. And the pedal shape, angle and ratio changed to provide instant response to changes in applied pedal force and greater controllability.
Brake cooling performance has also been improved by the adoption of straighter brake ducts which provide an increase in cooling airflow volume, minimizing brake fade even under protracted use.
Newly Adopted Drive Mode Select
A new Drive Mode Select system features up to five switchable driving modes -ECO, SNOW, NORMAL, SPORT/SPORT S and SPORT S+ (the latter optional on IS 350 F Sport models), to optimize the driver’s preferred combination of economy, comfort, performance and handling characteristics.
In ECO mode, engine output, throttle opening and gear selection are automatically modulated to optimize fuel efficiency under all driving conditions. The air conditioning system temperature and airflow volume are also cooperatively controlled, further reducing fuel consumption.
SNOW mode modulates throttle response to optimize vehicle traction and stability when starting on slippery surfaces.
In SPORT/SPORT S mode, engine speed and throttle responses are optimized to allow customers to enjoy a more engaging driving experience which exploits the full capabilities of both petrol and full hybrid powertrains.
Optional on models equipped with Adaptive Variable Suspension (AVS), SPORT S+ mode combines the SPORT/SPORT S mode’s enhanced powertrain output with coordinated control of the AVS and EPS or Variable Gear Ratio Steering (VGRS – standard on 3.5 liter RWD F Sport model) to minimize body roll, sharpen vehicle handling and optimize steering feel, rewarding drivers with the ultimate in sporting driving dynamics.
Enhancing the enjoyment of the new IS’s expanded breadth of driving style preferences, the ambient illumination of the driver’s instruments changes to a tranquil blue in ECO mode, while switching to red in both SPORT/SPORT S and SPORT S+ modes.
Adaptive Variable Suspension (AVS) System
The Adaptive Variable Suspension (AVS) system available on IS 350 F Sport models allows the driver to fine tune the IS F SPORT’s ride characteristics with a choice of two damper settings; NORMAL mode, for everyday driving comfort, and SPORT S+ mode, for improved body control and precise responses to steering input while cornering.
In response to driving operation, vehicle body motion and road surface conditions, AVS automatically adjusts the performance of the suspension at all four wheels and independently activates the adjustable damping force shock absorbers to fulfil a wide range of specific control functions.
When SPORT S+ mode is selected, the AVS system automatically increases the difference between inner and outer shock absorber damping through corners to further reduce vehicle roll.