So how does it perform? In most ways better than the second-generation car, though it may not immediately seem that way. That's because Subaru has sought to upgrade the STI's image by adding some of the refinement found in most other cars priced in the mid-30s. Is this a good idea? Have the STI message boards and blogs been filled by owners pining for less engine noise? Have they begged the aftermarket for quiet-tuning tweaks? I don't think so, and it seems like there's some risk of alienating the faithful in hopes of luring new and different buyers. Most of the gathered journos kind of missed the miscreant howling of the old car, and in any case if stepping up the interior poshness was the goal, the upgrades made to differentiate the STI from lesser Imprezae fall a tad short-at least to these jaded eyes. In any case, quieter cars often give the impression of underperforming louder ones, especially when there's no opportunity for direct back-to-back comparison. But rest assured, the new car certainly should perform as well as or better than the old one, especially in the handling department.
The single greatest dynamic improvement is the driver-programmable electromechanical limited-slip center differential. A torque-sensing mechanical locker varies the torque distribution from its default 41/59 front/rear split to as much as 55/45 or 25/75. Transitions within this realm are virtually instantaneous, whereas the previous purely electronic diff suffered some lag. If more is needed, an electric lock extends the torque-splitting range to 75/25 or 5/95. To sample the extremes of the system's capability, I ran back-to-back laps with the differential in its manual mode, with the torque bias set fully front and then fully rear. Bearing in mind that the mechanical part still does its magic before the electrons flow, I found the car much more willing to rotate a bit under power in the rear-biased mode. Conversely, it claws its way out of turns like a tiger chasing an impala and feels noticeably more neutral when biased for max grip at the front. On the smooth, dry tarmac at Fuji, it was nigh impossible to assess the sport programming of the VDC stability control. That's one of the big benefits of this center diff: Distributing torque mechanically keeps the wheels from spinning and inciting a torque interruption or brake intervention from VDC.
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