This gave teams greater latitude in design and materials including vehicle width, suspension geometry, aerodynamics, intercooler capacity and engine modifications.

[7] This led to a totally redesigned car, the WRC97, featuring modified camshafts, cylinder ports and combustion chambers.

[7] The Impreza WRC98 was an evolution of the earlier WRC97, with computer controlled active differentials in the front, rear, and centre, and an electronic throttle.

Subaru was the first rally team to implement this technology, which has been used on all WRC cars until it was forbidden by the 2011 championship rules.

[12][13] The new body had four doors (instead of two), and featured revised aerodynamics, improved weight distribution, and a lower centre of gravity.

[14] However, all the mechanical development from the previous year, including the engine, suspension, and drivetrain remained, with subtle refinements.

[16] It featured a revised look based on the updated Impreza production car introduced the previous year, with the "bugeye" headlamps replaced by the "blobeye" lamps.

[16] Technical improvements were made to the turbocharger and engine, aiming to increase torque at lower RPMs allowing greater driveability.

[19] The car featured more composite body panels, including front and rear wheel arches and bumpers in order to decrease weight.

[23][21] The WRC2007, a revised version of the earlier year's car, was introduced at the fourth round of the championship, Rally Mexico.

It featured new dampers, a different radiator and intercooler arrangement, as well as improved weight distribution, suspension geometry and differential set-ups.

[27] The car's engine, transmission and differential are individually oil sealed, so that they can be removed and replaced without fluid loss.

The transmission's lubrication system has a 4.5 litre capacity and includes an oil pump to help control differential temperatures, which usually operate around 100C.

[27] The transmission retains the roadgoing Impreza's H pattern but utilizes a hydraulically actuated and electronically controlled semi-automatic gearshift.

[28] The 2008 car was expected to benefit from a decreased polar moment of inertia due to smaller overhangs, and also featured a double wishbone rear suspension.