April 14, 2014 11:00 AM | By Jeremy Sinek for MSN Autos

2015 Subaru WRX STI first drive



2015 Subaru WRX STI (© Photo: Jeremy Sinek)
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  • 2015 Subaru WRX STI (© Photo: Jeremy Sinek)
  • 2015 Subaru WRX STI (© Photo: Jeremy Sinek)
  • 2015 Subaru WRX STI (© Photo: Jeremy Sinek)
  • 2015 Subaru WRX STI (© Photo: Jeremy Sinek)
  • 2015 Subaru WRX STI (© Photo: Jeremy Sinek)
  • 2015 Subaru WRX STI (© Photo: Jeremy Sinek)
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2015 Subaru WRX STI

STI remake keeps what was good, transforms what wasn’t

2015 Subaru WRX STI (© Photo: Jeremy Sinek)

Ojai, Calif. -- It’s been more than two years since we gave you the scoop on Subaru’s mainstream mild-child Impreza following its re-do for the 2012 model year. Earlier this spring, we spilled the beans on driving its long-overdue wild-child alter ego, the 2015 WRX. Now it’s the turn of the truly wicked WRX STI.

We won’t go into detail here about all the novelties that the 2015 STI shares with the 2015 WRX, such as the stronger, roomier, sleeker new body, upgraded interior, and the addition of Active Torque Vectoring to improve steering turn-in. Likewise the three trim grades, which offer basically the same escalating levels of appointments in both models.

There’s still plenty else to talk about -- paradoxically, because the 2015 STI is mechanically less changed from its predecessor than the WRX is. That relative changelessness, incidentally, also includes pricing: while the WRX’s base price was shaved $2,500 for 2015, the STI’s $37,995 price of entry is virtually the same as last year’s.

On the WRX, the direct-injection FA-series engine, the six-speed cable-shift gearbox and the electric power steering represent all-new hardware for 2015. The STI, conversely, keeps enhanced versions of last year’s basic hardware.

EJ engine is an oldie but a goodie

2015 Subaru WRX STI engine (© Photo: Subaru)

That means the 2.5-litre EJ-series engine carries over, though with tweaks to the ECU for improved driveability. Peak outputs remain 305 horsepower at 6,000 rpm and 290 lb.-ft. of torque at 4,000. A new “sound creator” strives to deliver a performance sound-track by channeling intake noise into the cockpit during aggressive driving. Last year’s six-speed manual gearbox continues essentially unchanged apart from some tweaks to enhance shift quality. Compared with the WRX’s new ‘box, most of the STI’s intermediate ratios are closer-spaced while top gear is a little shorter (3,000 rpm at 120 km/h vs. 2,800).

STI cultists may rage that there’s no horsepower increase for 2015, but Subaru apparently figures 305 hp is plenty for a compact car. We get the sense that engineering manpower is a precious resource at STI, so project manager Masuo Takatsu (whose background, coincidentally, is in chassis and suspension development) focused his resources on the handling. In particular, Takatsu says, the priorities were steering response, maximizing rear tire grip, and a flat ride.

Building on the new body’s heavily reinforced structure, Takatsu’s team reworked just about everything else that affects suspension performance – mounting points, geometry, springs, dampers, bushings and stabilizer bars. The springs are stiffer by 22 per cent up front and six per cent in the rear.

The steering assist remains hydraulic, bucking the modern trend to electric, but the ratio has quickened from 15.0 to 13.0:1. A 125 per cent stiffer torsion bar, and rack mounting bushes that are five times more rigid, may provide a clue to the cause of some of the old STI’s steering foibles. Tire sizes remain unchanged at 245/40R18, as do the Brembo brake rotor dimensions. But the wheel designs are new (as well as a full kilogram lighter) and a five-twin-spoke BBS design is exclusive to the STI Sport-Tech. The W-rated Dunlop tires are now ST Sport Maxx RTs.

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