The starting point for the new rally car is the 2006 model Subaru Impreza road car. As the basis of a rally winning machine, few cars can match the competitive pedigree of the Impreza. First launched in 1992, the road car has developed in tandem with its rallying counterpart and over the last twelve seasons, and 46 WRC victories, lessons learned on the rally stages have been fed back into the production model.
Already renowned for its agile handling, leech-like roadholding and symmetrical all-wheel drive security, the latest Subaru Impreza forges even stronger links with its World Rally Championship stablemate.
Like the preceding model, both rally and road versions were styled in Japan by the FHI design team led by Andreas Zapatinas. Externally, a key new feature is the spread-wings mesh front grille with a centre section resembling an aeroplane fuselage and sweeping outer sections mimicking the wings. Fuji Heavy Industries Ltd, the manufacturer of Subaru, has its origins as an aircraft maker.
New headlamps have a 3-D effect with cylindrical lamp units. The rear lamps are also 3-D, with similar cylinders encircled by claw-type strakes. Revised front bumpers with concave horizontal corner spoilers smooth the airflow down the side of the car. In addition, the saloon features vertical air intakes at the side of the bumper for enhanced brake cooling.
A new design of side-skirts adds to the sports stance, being better integrated with the overall body design and featuring sweeping swage lines that continue to flow into the rear bumpers. Also new is a roof vane covering the top half of the rear window. This compliments the massive high-rise boot spoiler by deflecting airflow from the top of the roof under the boot spoiler, increasing downforce and high speed stability.
From the start of the 2006 WRC season, leading cars must comply with revised technical regulations which, among other things, outlaw engine water-injection and active control of front and rear differentials. So, ten years after the introduction of the computer controlled units, the Subaru team faced the engineering challenge of making their car go just as well but with traditional, mechanical differentials.
The two-liter flat-four engine had to be adapted to meet the new technical regulations but Lapworth’s team wanted to go further than that. "We had to take into account the loss of the water injection but we’ve done a lot of work on the control, fuel system, lightening of components and friction reduction. We’ve ended up with something which is more powerful, delivers more torque and is more responsive and lighter than last year’s engine."
Back in 1999 Subaru was the first WRC manufacturer to introduce an electronically operated semi-automatic gearbox. This year, the ground-breaking six-speed transmission is further refined with a new hydraulic system which gives a better control of the centre differential and a faster gear change. The result is that the already rapid gear change is now faster than most Formula 1 cars.
Elsewhere in the car, from front to back, hundreds of other smaller revisions were made to areas including the wiring loom, fuel system, electrical systems and the location of systems in the cockpit.