Press Release
NVH (NOISE VIBRATION AND HARSHNESS)
Particular attention has been paid to the reduction of external noise intrusion and the acoustic characteristics of the new IS’s cabin. An abundance of sound absorbent and insulating materials located throughout the interior envelope includes newly developed, foam-type asphalt sheeting to further reduce weight. Rubberised underbody floor covers and sound absorbing, Polyethylene Terephtalate felt and Styrene-Butadiene rubber resin rear wheel arch liners combat noise intrusion from water and gravel splatter. The floor carpet features an absorption-insulation-absorption material sandwich to minimise road noise penetration.
The detailing of external bodywork seals, weather strips and door and window frame mouldings contribute to greatly reduced wind noise. Triple seals have been adopted for all four doors, with additional door sill seals to eliminate air ingress. A rubber seal is fitted around the entire bonnet rim, and flush mounted mouldings to the windscreen and door glazing further combat wind noise. The windscreen itself is equipped with an acoustic inner film boasting high noise damping characteristics, leading to a cabin noise reduction of up to 4 dB at idle.
In a further example of Lexus’ attention to detail, unique, perforated, sound absorbent sun visors have been incorporated, their proximity to passengers heads resulting in a significant reduction in wind noise from windscreen head and “A” pillars.
SUSPENSION
The new Lexus IS is equipped with a double wishbone front and multilink rear suspension configuration which combines legendary Lexus ride comfort with the excellent handling and dynamic abilities.
Front Suspension
The front, high-mount, double wishbone suspension system combines a lightweight, forged aluminium knuckles with a high tensile steel lower arm and a hollow anti-roll bar to reduce unsprung weight.
The new suspension configuration features a 35% higher camber angle than that of the current IS, which improves steering wheel centring, enhances negative camber to the outside wheel when cornering, and improves steering feedback. An 18% higher kingpin angle improves straight line stability, a 10% increase in caster trail promotes a more stable steering feel, and a 22% reduction in roll centre height provides improved cornering stability with reduced body roll.In addition, new, forward mounted power steering gear allied to low toe variation along the suspension stroke promote a more linear yaw response, precise steering control and excellent straight line, high speed stability.
Rear Suspension
To the rear, an advanced multilink set-up with toe control arms and an aluminium rear axle carrier combines stiffer suspension component materials with a reduction in unsprung mass for excellent ride comfort with high cornering stability. The adoption of a double-linked upper arm and integrated bearings and hub combines optimised geometry and high rigidity with significant weight reduction.
The utilisation of a multilink configuration facilitates the optimum balance of handling, stability and ride comfort: The upper arms contribute to a reduction in upward spring motion, the mid-arm contributes to reduced body roll, and the lower arm provides an improved anti-lift / anti-squat ratio. Moreover, aligning the shock absorbers along the same, lower axis as the coil springs facilitates a wider boot loadspace.
SHOCK ABSORBERS
The next generation Lexus IS features new, high performance, monotube shock absorbers. The new monotube configuration also dissipates heat more efficiently, resulting in better control and a reduction in high-use fade.
A large, 45 mm piston diameter offers a sharper shock absorber response to any vertical wheel movement, a new fluid and oil seal design combine to provide greater damping force under smaller compression, and a pyramidal valve stack design reduces damping force under high piston velocity – reducing impact shock when, for instance, the vehicle drives over a bump at high speed.
Large diameter, liquid-filled bushing to the lower suspension arm further reduces the transmission of vibration, and rebound springs are incorporated in all four shock absorbers to control roll angle in extreme situations.
The IS 250 Sport is equipped with a bespoke suspension configuration featuring stiffer spring and damper settings that also decrease ground clearance by 10 mm. This further reduces body roll and improves handling characteristics.
ELECTRIC POWER STEERING (EPS)
The next generation IS features a brand new, speed sensitive, electrically assisted power steering (EPS) system. It is superior to comparable hydraulic systems in offering perceptible fuel savings, noise free operation and, through the location of the steering gearbox ahead of the front axle, smooth, linear feedback to the driver. Both the DC motor and reduction mechanism are now built into the ultracompact steering gear housing.
The system’s electric motor uses 42 V AC current for more prompt response to steering inputs. Unlike conventional systems, wherein power assistance is determined solely by vehicle and engine speed, the Lexus IS’s EPS also registers steering angle and torque in calculating the degree of assistance required at any time.
Key steering parameters have been amended from the current IS model range to create a quicker, more direct steering feel. The number of turns lock-to-lock had been reduced from 3.00 to 2.91, and the gear ratio has been simultaneously reduced from 14.5 to 13.5. Furthermore, the new IS delivers a class-leading turning circle of 5.1 m.
In IS models fitted with Lexus’ unique active safety system, Vehicle Dynamics Integrated Management (VDIM), EPS is incorporated within the system to promote smoother “on-the-limit” vehicle behaviour through unobtrusive intervention. Via the EPS actuator, VDIM will provide steering assistance to reduce torque steer under braking on surfaces of varying grip, as well as introducing steering torque assistance in both understeer and oversteer conditions, helping the driver to optimise the front wheel steering angle and maintain vehicle stability with minimum input. Unlike conventional stability control systems which simply correct the vehicle’s trajectory when under or oversteer are detected, VDIM acts in anticipation of these dynamic thresholds with a discrete and smooth intervention designed not to detract from performance driving pleasure.
BRAKES
The new Lexus IS features powerful, 298 x 28 mm ventilated front and 291 x 10 mm rear disc brakes throughout the range. A new, brake-fade pressure compensation system constantly monitors brake performance by comparing brake pedal effort with vehicle deceleration, applying additional pressure to minimise the effects of brake fading. In addition, a stiffer brake hose material displays lower distortion under pressure for improved braking feel, and new, high friction coefficient brake pads further increase the IS’s braking efficiency.
A new, link-type variable ratio brake pedal provides a progressive action combining optimum low-deceleration feel with maximum high-deceleration power.
Via this new brake system, the next generation IS deploys a comprehensive range of active safety braking functions: Anti-lock Brakes (ABS), Traction Control (TRC), Vehicle Stability Control (VSC), Brake Assist System (BAS), Electronic Brake-force Distribution (EBD) and Hill-start Assist Control (HAC). In models equipped with automatic transmission, HAC allows the IS to pull away smoothly on a gradient without rolling backwards - this is achieved by maintaining brake pressure for five seconds after the brake pedal has been released.
IS models fitted with Vehicle Dynamics Integrated Management also benefit from VDIM’s integrated activation of these braking, stability and traction control systems, further improving the overall dynamic performance of the vehicle.
WHEELS AND TYRES
The new Lexus IS will be available with a choice of bespoke, 16", 17" and 18" alloy wheels, determined by the model range specification.
Vehicles featuring 18" wheels are fitted with wider 255/40 R 18 Dunlop SP Sport Maxx tyres at the rear, specially developed for the Lexus IS to provide superior grip under all road surface conditions.
The next generation Lexus IS is offered with a choice of two power plants: a 153 kW / 208 DIN hp, 2.5 litre direct injection V6 petrol engine, and Lexus’ first diesel, a 4-cylinder, 130 kW / 177 DIN hp, 2.2 litre state-of-the-art unit which will dramatically strengthen Lexus’ position within this highly competitive market segment.
Both engines are mated to a newly-developed, 6-speed manual transmission. The new V6 unit may be mated to an optional, 6-speed automatic transmission featuring sequential, paddle-shift control.
POWERTRAINS
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First ever Lexus diesel engine: an aluminiumblock, 130kW/177 DIN hp 2.2 litre common rail unit offering classleading refinement
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Lexus Clean Diesel Technology ensures the IS 220d is one of the cleanest luxury diesel cars for combined NOx and PM emissions
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Shorter differential gear ratio for IS 220d equipped with 18’’ wheels, giving 30% improved in-gear acceleration
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New, 153 kW/208 DIN hp direct injection V6 petrol engine featuring Dual VVT-i
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Optional 6-speed automatic transmission with sequential paddleshift mode
2.2 LITRE DIESEL
Fulfilling the most exacting standards of Lexus refinement, the new 4-cylinder, 2,231 cc common-rail diesel unit features an aluminium block to optimise weight saving and driving dynamics in the new IS 220d. The engine includes several unique design features and, as befitting the marque, particular attention has been paid to reducing noise and vibration to levels unprecedented within a diesel engine.
The new Lexus diesel generates 130 kW / 177 DIN hp at 3,600 rpm and an impressive 400 Nm / 295 lb.ft of torque between 2,000 and 2,600 rpm. The IS 220d will accelerate from 0-100 km/h in 8.9 seconds and on to a top speed of 215 km/h, yet return fuel consumption figures of just 6.3 l/100km in the combined cycle.
Integrating 3rd generation common-rail technology with piezoelectric injectors, the new Lexus powerplant combines an exceptionally high injection pressure of 1,800 bar with one of the world’s lowest diesel engine compression ratios of 15.8:1. A low compression ratio reduces the compression build-up inside the large diameter combustion chamber, minimising the noise and vibration attendant to each explosion and eliciting exceptionally quiet combustion.
Via high-flow, high speed injectors featuring 10 holes with a 0.13 mm nozzle diameter, the common rail system can produce up to 5 separate injections per cycle.
The new Lexus diesel features several additional anti-noise and vibration measures: The adoption of a balancer shaft within the unit offers significant reduction in engine “booming” noise between 2,000 and 3,000 rpm. A urethane engine cover and three-layer heat insulator combine with urethane spacers on the upper surface of the inlet manifold, oil cooler backside and oil pan rear to further curtail engine noise. A variable back-pressure exhaust system minimises exhaust sound at low speeds, and incorporates twin ball joints to minimise vibration and cabin noise intrusion.
These numerous NVH reduction measures reward the new Lexus IS 220d with a particularly quiet cabin environment, delivering an Articulation Index - measured through the use of random words in conversation - superior to that of many petrol fuelled powerplants.
The new 2.2 litre diesel is further equipped with Lexus Clean Diesel Technology, a package of innovative features that aim to reduce emissions substantially below EURO IV requirement levels. Key to this technology is the Diesel Particulate NOx Reduction (DPNR) 4-way catalytic converter - the only catalyst in the world that reduces NOx and PM (particulate matter) simultaneously. With NOx and PM emissions of respectively 0.159 g/km and 0.0019 g/km, the Lexus IS 220d is one of the cleanest diesel luxury cars on the market for combined values of these emissions.
2.5 LITRE V6 PETROL
The new, chain-driven double overhead camshaft, 24 valve, 2,500 cc V6 petrol engine features a compact design and reduced weight (180 kg service mass). Being no heavier than the current IS 2.0 litre powerplant, the new 2.5 litre V6 employs an aluminium die-cast cylinder block and intake manifold, and a resin-made intake chamber. The overall engine assembly is made lighter and more compact through the installation of the water and oil pumps within the chain cover.
Featuring direct injection technology which affords this unit the highest injection pressure amongst petrol engines (130 bar), it develops 153 kW / 208 DIN hp at 6,400 rpm and
a class-leading 252 Nm / 186 lb.ft of torque at 4,800 rpm, awarding the new Lexus IS 250 performance figures of 0-100 km/h in 8.4 seconds and a top speed of 230 km/h. The highly sophisticated 2.5 litre unit returns 9.8 l/100 km (9.1 l/100 km for models equipped with automatic transmission) in the combined cycle.
The new V6 also employs an electrically activated, 2-stage Acoustic Control Induction System (ACIS). This system divides the intake manifold into 2 sections, with an intake air control valve in the bulkhead opening and closing to vary the effective length of the intake manifold in accordance with the engine speed and throttle valve angle. This increases the power output in all ranges from low to high speed. The ACIS electric actuator is bonded to the plastic intake chamber through an advanced laser welding process.
Swirl Control Valves (SCVs) are installed in the intake manifold -one per cylinder. Via optimised intake port diameter and length, SCVs stabilise combustion at a low coolant temperature and allow the generation of high torque at low rpm.
The adoption of Dual VVT-i (Variable Valve Timing-intelligent) to both intake and exhaust camshafts also significantly ameliorates engine performance. Able to control intake and exhaust camshafts through angles of up to 40 and 35 degrees respectively, Dual VVT-i allows a greater intake/exhaust valve overlap, benefiting both low-end and top-end torque as well as contributing to a reduction in exhaust emissions and better cold-start performance.
Roller rocker arms have been adopted for the chain-driven valve system, the marked reduction in friction between the cam and sliding components helping enhance fuel efficiency. In addition, a concave camshaft profile increases valve lift to boost output. The system requires no valve clearance adjustment over the life of the vehicle. All exhaust components are fabricated in stainless steel. The adoption of a dual-tube exhaust manifold construction enhances corrosion resistance whilst reducing both heat-loss and noise. In comparison with the current IS 300 exhaust system, enlarged dual main mufflers with variable back-pressure valves and a long-tail structure both reduce low-frequency booming noise - 7dB less at 1,200 rpm - and reduce high rpm back-pressure by 30% to enhance engine output.
