Improved, Slicker-Shifting TransmissionsAll new Imprezas receive slicker-shifting five-speed manual transmissions, while the optional four-speed automatic gearbox is more fuel-efficient and offers the driver the opportunity to change gear manually during sportier driving.
The Impreza 1.5R now has a double-cone synchroniser for second gear giving a lighter change while a hydraulic clutch replaces the cable arrangement for smoother, quieter operation. In addition, the 1.5R has revised 2nd 3rd, 4th and 5th gear ratios while the WRX has revised 1st, 2nd and 3rd ratios. A four-speed automatic transmission provides smoother changes with greater sensitivity to the driver’s wishes.
It is more efficient, saving fuel, because a slip lock-up device reduces wasted engine revs. In addition, advanced electronics – linked to an electronic throttle – match engine speed with the best gear for any given situation.
The standard low-ratio transfer ’box on manual Imprezas effectively provides 10 speeds. This is useful when towing or covering difficult road surfaces, providing extra engine braking – and therefore greater control – at low speeds.
As with previous models, the full-time all-wheel drive transmission features a 50/50 front to rear torque split on manual models and 60/40 on the automatic. However, the split varies according to changing conditions.
The manual Impreza has a centre differential with viscous coupling which senses which axle has the better grip and distributes torque accordingly to minimise the risk of wheelspin.
The Impreza 2.0R and RX plus the WRX benefit from Subaru Vehicle Dynamics Control as standard. This has previously only been available on certain automatic versions of the Forester and Legacy/Outback.
Subaru Vehicle Dynamics Control uses sophisticated sensors to detect side to side and front to rear slip plus sudden steering movements. It controls oversteer /understeer and potential loss of control by braking individual wheels and cutting engine revs – all in milliseconds.
On automatic models, a similar function to the viscous coupling is carried out by Subaru’s sophisticated Active Torque Split system. This employs electronics,
sensors and a multi-plate hydraulic transfer clutch. Again, on 2.0 litre models, SVDC is standard.
Finally, the Impeza WRX changes its previous viscous rear limited-slip differential to a mechanical one which reduces weight and improves fuel consumption.
Passenger And Pedestrian Safety Boost
Both occupants and pedestrians are well protected by the latest Impreza thanks to a whole series of safety measures aimed at achieving the highest standards of both occupant and pedestrian safety.
Curtain and side airbags are now fitted to all models together with driver and passenger airbags. Front seatbelts have pre-tensioners, most models have anti-whiplash head restraints and all front seats have energy-absorbing backs.
The brake pedal is energy-absorbing, being designed to snap away under severe impact, protecting the driver’s lower limbs. In the rear seat are two ISOFIX-compatible child seat mountings.
The passenger airbag is dual-stage which provides progressive protection matched to the severity of the impact and the standard anti-lock brakes (ABS) come with electronic brakeforce distribution (EBD). This juggles the braking force between front and rear wheels according to load shifts during deceleration. All Imprezas have front ventilated disc brakes and solid rear discs.
Outside, pedestrian injury is reduced thanks to a more rounded contour to the top of the front bumper, a gently curved bonnet and windscreen wipers which collapse, softening any impact.
High tensile steel of varying thickness is used extensively throughout the body, providing good crushability where needed while protecting the passenger area.
Not only does the elimination of the previous Impreza’s front subframe reduce body weight by 20 kg but the new structure better dissipates front impact forces.Published 23 August 2007