Technical Details of Impreza Wrx Sti

From 3arf

It's been a decade since the first STi-tweaked Impreza WRX. If you've lost count of the various "versions" that have come and gone since then, don't feel bad. You're not losing touch with your inner-lout, because even Subaru has stopped caring. While the boys at Subaru Tecnica International will still crank out the odd Version 9.6 With A Twist Of Mango special edition, the mainstream models no longer wear those mad monikers. The latest is simply the "2006 STi".

Actually, it looks pretty much identical to the 2005 STi. And maybe the 2004 STi. So what's changed?

Plenty. Wrench the three-spoke wheel into a 35km/h corner with as much clumsy aggression as you dare and it's clear that the new STi is now that bit closer to being a steering and suspension superhero. Messages from the road below are communicated clearly and quickly, understeer is simply not in the handling equation and the rear end wriggles in a very naughty fashion as you put the power down past the apex.

Yep, it's still four-wheel-drive. But it serves up the balance and feel of a rear-driver without the pants-wetting sensation when you over-reach your own abilities.

There have been major changes under the STi's squared-off sheet metal. A "canon mount" steering rack housing is claimed to improve response, while new damper valves cut down kickback on bumpy backroads.

The STi's front suspension housing is strengthened to enhance strut firmness and accommodate the more substantial eight-inch-wide alloy wheels and Bridgestone Potenza RE070 235/45 R17 tyres.

Front and rear suspension links are now made from aluminium, while a unique wheel mounting and bearing design increases strength between axle and wheel. The caster angle has been increased by 1.25 degrees and increased-diameter anti-roll bars are fitted from and rear.

A front helical limited slip differential lies up front, which can direct torque to the outside wheel around turns. Meanwhile, a yaw sensor for the four-wheel-drive system reduces understeer by shuffling power forwards through tight turns.

The rear track is up 10m to 1495mm and the wheelbase has been stretched 15mm to 2540mm. A new underbody cover is claimed to offer both protection and improved aerodynamics.

It's a lot to take in. But then the STi is a lot of car even if you're blissfully ignorant of the technology underpinning it. The 2.0-litre turbo boxer-four still officially adheres to Japanese carmakers' voluntary power cap of 206kW (sure, if you say so boys) but torque has been tweaked to 412Nm at 4400rpm, up 18Nm on the old car.

Be Mister Brutal and the super-Subaru will rocket to 100km/h in 5.5 seconds, providing you've mastered the firm but deliciously direct close-ratio six-speed gearbox. In fact, in no time at all you will have slammed into the brick wall that is the Japanese domestic market speed limiter at 180km/h.

The STi is just a big, bloody dangerous toy, a fact attested to by the number of rally-wannabe buttons and dials in the cabin. The centrally mounted tachometer has an adjustable rev-limiter and shift-warning light, the backlit dials tease you by flipping around to max speed positions when you turn the key and there's a manual water-spray control for the turbo intercooler.

The STi's Direct Control Centre Differential (DCCD) carries over into the new model. Leave it in auto and the car decides for itself how to split the torque front to rear. Select manual and you can dial up to 65 percent of power to the rear wheels and keep it there. Given how tail-happy the STi can be on wet roads, good luck with that...

Mental it may be, but the STi doesn't have to drive you mad around town. The figure-hugging sports seats (trimmed in a new super-grippy fabric) are not a bad place to be on a drive down to the video store and the ride, although abrupt on rippled urban roads, isn't entirely unfriendly at 50km/h.

In one sense, the chassis technology now crammed into the STi is simply playing catch-up with the Mitsubishi Lancer Evo VIII. In another sense, it's pretty bloody exciting and who cares how it came about.

While the drive has become that much more dramatic, you have to be very keen/sad indeed to distinguish the 2006 from the previous car. At least at a glance. The body of evidence is at the rear, where you'll glimpse (maybe) a reshaped bumper and (probably) some tacky-looking wheelarch extensions to cover the wider track and gung-ho new footwear.

Otherwise, it's styling business as usual: the blokes at STi still attack the WRX with the ugly bat. But what a beautiful drive.

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