2015 Subaru WRX STI First Look
Improving the Evolution
Now that the performance of the all-new WRX has sunk in, Subaru has hit us again with the new WRX STI.
Per expectations, the STI takes the already improved WRX formula and adds extra power and grip. The 2.5-liter turbocharged boxer four-cylinder engine carries over with 305 hp and 290 lb-ft of torque, or just slightly more than the top-shelf Mitsubishi Lancer Evolution. It's matched to an improved six-speed manual gearbox that our test of the standard WRX shows to be a slick, quick-shifting box with short, crisp throws.
From the transmission, power goes to Subaru's Driver Controlled Center Differential, which gets three performance modes and six manually controlled differential settings. All those electronic settings are augmented by a mechanical limited-slip feature that defaults to a 41/59 front-rear torque split. Power is handled at the front axle by a helical gear limited-slip differential and at the rear by a Torsen torque-sensing electronically controlled limited-slip differential.
On top of all that is Subaru's new Active Torque Vectoring software, an upgrade to the standard Vehicle Dynamics Control stability- and traction-control system. The active torque vectoring, like on the standard WRX, brakes the inside wheel and sends torque to the outside wheels during cornering. Vehicle Dynamics Control, meanwhile, can be fully switched off.
At the ground, larger 18-inch forged BBS wheels are wrapped in wider 245-series summer performance tires for even more grip than the already Velcro-like WRX. Behind the gold shoes are big Brembo four-piston front and two-piston rear calipers. Brake rotors are 13 inches and 12.4 inches at the front and rear, respectively. Unlike the standard WRX, the STI's front wheels are still actuated by a hydraulic power-assist rack rather than electric.
With more motor, bigger brakes, and fatter tires, not to mention an STI-tuned suspension, expect all performance metrics to improve despite the number of carryover parts. We expect the STI to hit 60 mph in five seconds or less and run the quarter mile in the low 13-second range. Lateral acceleration may well scratch a full 1.0 g, and the figure-eight time should drop to near 25 seconds flat. Braking may well drop below the 100-foot mark.
For comparison purposes, here's the skinny on related cars. The standard 2015 Subaru WRX with a six-speed manual hits 60 mph in 5.5 seconds and the quarter-mile mark in 14 seconds flat at 98.1 mph. Lateral acceleration peaks at 0.96 g and our figure-eight test is bested in 25.3 seconds. Braking from 60 mph happened in just 106 feet.
The last WRX STI we tested, a 2011, needed 5 seconds flat to hit 60 mph and did the quarter in 13.6 seconds at 99.2 mph. It weighed about the same as the 2015 WRX we just tested, or about 3300 pounds. The 2011 pulled 0.93 g on the skidpad and made it around the figure eight in 25.6 seconds. It stopped from 60 mph in just 110 feet.
Surprisingly, the old STI was not the king of Subaru's hill. That honor goes to the WRX Special Edition, which went on a diet and dropped its 60-mph sprint to 4.7 seconds and the quarter-mile result to 13.5 seconds at 100 mph dead. Braking was an equally impressive 106 feet, while figure-eight performance was unchanged at 25.6 seconds. Slightly behind was max lateral acceleration, at 0.92 g.
The last Mitsubishi Lancer Evolution X SE we tested, meanwhile, needed just 4.5 seconds to hit 60 mph and only 13.3 seconds to run the quarter mile at a trap speed of 103.4 mph. It was also quicker than any of the Subies around the figure eight, doing the deed in 25 seconds flat. Max lateral g rang in at a directly competitive 0.93, but braking was a weak point, with a 112-foot stopping distance from 60 mph.
A slightly disadvantaged, front-drive Ford Focus ST is also a legitimate contender. Down considerably on power, the ST is a bit slower to 60 mph, needing 5.9 seconds, and likewise slower through the quarter mile in 14.6 seconds at 95.7 mph. Turn the wheel, though, and things change. The ST will pull 0.97 g on the skidpad and knock off the figure eight in 25.5 seconds. Braking from 60 mph needed just 108 feet.
A special WRX STI Launch Edition will be available in limited numbers with gold wheels, STI short-throw shifter, blue interior accent stitching on the leather-wrapped steering wheel and Alcantara-covered center console arm rest, and blue leather inserts on the door panels and performance seats with black contrast stitching. Sales start in the spring with pricing likely to remain in the $35,000 range.