Car Design News: New Toyota Auris: In Depth

3: Driving Experience

Engaging driving experience

All-new platform
Developed in Europe for Europe
Excellent driver control and handling
Excellent low noise levels

When creating Auris, Toyota has designed a C-segment hatchback based on a newly developed platform that not only looks the part, but actually delivers an experience that begins the moment you sit in the driving seat.

Yoshihiko Kanamori, Chief Engineer for Auris, explains: â€œWith a design that raises expectations of great driving performance, we needed to focus on every aspect of quality and comfort. This counts for the high quality that must be felt when sitting in the driverâ€™s seat, to the operational touch and sound of each switch, to the well dampened engine sound that flows inside the car. And, of course, we needed to provide engine performance, handling and stability that surpasses levels of current competition.â€�'

With the highly competitive European C-segment market in mind, every aspect of Auris has been fine tuned to meet the needs and desires of European buyers.

As chiefengineer Kanamori explains: â€œDevelopments since the production of the base platform have been carried out by carefully refining the model through locally tailored, European tests. The development team has paid attention to every detail from the driving position to the chassis tuning to ensure the ultimate driving performance.â€�'

Driving cockpit

Designed around the driver
All-new front and rear suspension
Precise power steering

The focus of the new Auris interior is to create a sporty and superior quality image.

Front seatsare body hugging with a firm shoulder area, long seat cushion and firm side supports. The sports-style, three-spoke steering wheel is robust with a thick gripping surface and semi-elliptical centre padding, designed to echo the shape of the Toyotalogo. Main meters are Optitron-design with three-dimensional layered display.

With the bridged centre console, the direct gear shiftlever is moved closer to the natural position and the parking brake lever is immediately to hand. The overall effect is to create a driving cockpit with all major controls at your fingertips.

The wide choice of advanced and refined high performance engines are matched with carefully selected transmissions and an all-new, rigid platform featuring fully redesigned suspension, brakes and steering. The combined effect: stable high speed driving performance, engaging and responsive steering, excellent handling and superb ride comfort.

The newly developed front suspension utilises a variation of the high effective MacPherson strut, known as an L-arm MacPherson strut. This compact and highly rigid design brings the strut in-board from the wheel hub which allows wider track, excellent noise and vibration suppression, and superior stability.

The suspension geometry has been optimised with careful attention to the positioning of the lower L-arm, the camber angle, caster angle and king-pin inclination. All of this results in excellent straight line stability with good, precise steering response.

The lightweight anti-roll bar has highly precise ball-joint mountings to the strut casing and bushesembedded in the suspension member to ensure consistent rigidity and a highly efficient layout.

Auris is available with two different, highly efficient rear suspension designs to suit the performance characteristics of specific models.

At the top of the range, with the powerful D-4D180 Clean Power Diesel Engine, Auris is equipped with an all-new double wishbone rear suspension for maximum high performance stability while retaining a compact design. The double wishbone design allows engineers to isolate specific force inputs and optimise the suspension bushes and mounts accordingly. This axle design can handle the high specific forces and torques inside the suspension system which a strong powertrain like the D-4D180 creates in sporty driving situations â€“especially during throttle lift-offsituations. The use of the double wishbone layout successfully eliminates all destabilising forces.

Highly rigid, lightweight high-tension steel is used to form the trailing arm, upper arm and one lower arm. Toe adjustment of the second lower arm is used for accurate stabilisation effects of the suspension geometry. At the same time all bushings are optimised for both compliance and rigidity.

Separate layout coil springs and dampers create a compact design which accommodates the low, flat body floor and spacious cargo area, improving the damper efficiency at the same time.

All other models in the Auris range benefit from a highly effective and super-compact torsion beam rear suspension which creates a spacious cargo area and provides both superior handling stability and ride comfort.

The suspension layout, with optimised settings throughout, separates the coil spring and damper while allowing a wider space for the cargo area. The torsion beam itself sits behind the fuel tank and ahead of the spare wheel carrier, contributing to the flat underfloor.

The torsion beam suspension and newly-designed slanted trailing bushes allow precise control and toe changes in response to inclining lateral forces during cornering. Excellent stability is achieved in straight line driving while toe-in during cornering ensures stable handling and a secure feel.

Of course, stable suspension is critical â€“but drivers engage with the car through the throttle and steering response. Auris adoptsa newly developed Electric Power Steering (EPS) with a quick ratio of 14.44 and excellent speed-sensitive feel. At just 2.9 turns, lock to lock, there is precise and instant driver control.

The EPS contributes to fuel economy by consuming power only when steering force assistance is needed and does not require hydraulic fluid. The compact, high output motor and torque sensor are built into the steering column, providing direct and highly efficient steering assistance for enhanced feel.

Engaging driving experience

Excellent aerodynamic shape
Low noise and vibration levels

Almost contradicting its engaging driving performance, Auris is quiet and comfortable â€“ indeed it is one of the quietest cars in its segment. This has been achieved through a carefully balanced package of superior design, excellent aerodynamics and rigid body structure.

For instance, the exterior lines of Auris are not just striking to look at. They also clearly demonstrate the superb build qualityof the car and they also provide a great aerodynamic shape that cutsfuel consumption, reducing noise and improving stability at the same time.

Fluently formed shapes, with minimal differences in surface levels and tight shut lines, ensure smooth air flow across the major surfaces. Even the aerodynamics under the body have been optimised with a flat engine undercover and suspension parts shaped to achieve optimum aerodynamic effect. These efforts are complemented by a redesigned fuel tank, exhaust pipe and rear floor shape.

The rear bumper ground clearance is raised to increase air flow and the rear styling minimises wind swirl from the roof.

The front bumper acts as an aerodynamic â€˜splitterâ€™device, smoothing out the airflow around and below the body sides while its broad width (plus front and rear wheel spats) helps shield the wheels during high speed driving. This helps achieve superior straight line stability and excellent steering response.

This attention to detail extends to the flush surface mounting of the acoustic windscreen glass, reshaping of the louver at the back edge of the bonnet and even the airflow over the windscreen wipers.

Underneath the body, mostly hidden away in the platform design and superior build quality, further measures reduce all possible transfer of noise and vibration. Careful placing of cross-members and selected reinforcing pointsensure a rigid floor panel and suppress movement in the body framework. A cross member in the dash panel reduces shake and vibrations and ensures a high level of quietness.

Sound absorbing metal coating and the use of dampening material has been carefully positioned through the dash and floor to maximum effect while foam sound insulation is placed in the body frame. A cell-type sound absorbing material is used for the engine undercover and a bonnet insulator is available to create an air layer between the bonnet panels.

Further sound insulation is placed throughout the interior with roof silencersbetween the roof reinforcements, sound insulating carpetsand felt in each trim panel. Finally,road noise is further suppressed by installing sound absorbing material around the front and rear wheel arches.

Chiefengineer Kanamori says: â€œIt was our aim to create superior qualityfeeling by focusing on reducing Noise, Vibration and Harshness (NVH) which plays an important role in this. From the beginning, we made sure we had a great design based on a rigid vehicle structure to reduce noise in the cabin.â€�'