Why You Can Trust CNET 2015 Subaru WRX STI review: Subaru WRX STI is a terrific track tool that's brutal on the boulevard
With tons of power on tap and gobs of grip, I found myself giggling with glee while the Subaru coaxed me to push just a bit harder next lap.
- North American Car, Truck and SUV of the Year (NACTOY) Awards Juror
Editors' note, June 16, 2014: I was recently able to take a second look at the 2015 Subaru WRX STI, so we're updating the our track-centric first look to reflect new information about the available tech and daily driving experience.
The Good
The Bad
The Bottom Line
Imagine for a moment that you're on your favorite driving road, ready for a quick and curvy blast, but instead you find yourself stuck behind some tourist who's slowing your ride to a crawl, thanks to his or her unfamiliarity with the road. Imagine the frustration that you'd feel; now imagine that the road is your favorite race track and that both you and the slowpoke ahead are both driving 300-plus-horsepower, all-wheel-drive, race-bred sport sedans. What a waste of speed! This was my first lap piloting the freshly announced 2015 Subaru WRX STI 'round Mazda Raceway Laguna Seca, my frustration increasing exponentially with each turn as I balanced trying not to bully the poor guy with wondering how bad of a slap on the wrist I'd get from our hosts for blowing past him at this no-passing-allowed exhibition event.
Just when I was ready to bend the rules, the slowpoke prematurely dipped into the pit lane, leaving me with a clear shot at the track's long front straight and a sudden outlet for the red mist that had been building over the lapping session. Perhaps it was this red mist that caused me to misjudge the braking point for the track's infamously tricky Turn 2 hairpin, but it was certainly the genius of the 2015 STI's revised symmetrical all-wheel-drive system that saved my bacon in the end.
The STI
Based on the newly announced Subaru WRX (and, ultimately, the Impreza sedan), the 2015 WRX STI is the hottest, fastest ride that the automaker is currently producing. Like the WRX, this is no mere performance package for the docile Impreza -- it's a whole new vehicle.
Peek through the functional hood scoop and you'll see the top-mount intercooler that chills and condenses the intake air that's being crammed into the 2.5-liter Boxer engine by the STI's turbocharger. That engine is virtually unchanged from the previous generation of the WRX STI and retains the performance as well as the Boxer burble that we loved in its last appearance. The engine also still feeds premium fuel into its combustion chambers by way of port injection, rather than the more modern direct-injection setup used by the standard 2015 WRX's new 2.0L. Given that, there should be no noticeable gains in fuel economy, but the numbers that you're probably interested in are the output, which is stated at 305 horsepower and 290 pound-feet of torque.
That power flows through a close-ratio six-speed manual transmission that is also largely unchanged from the previous generation, retaining its solid shifter linkage where the standard WRX moves to a cable linkage. This, along with a few improvements engineered into shifter mechanism, give the STI an improved shifter feel with better feedback than the WRX, which is a good thing. Enthusiasts will rejoice in knowing that the WRX STI will be made available only with this manual transmission; there's no automatic or CVT option.
The engine and gearbox may not have changed, but the rest of the vehicle around them certainly has, starting with the automaker's Symmetrical All-Wheel Drive system. Utilizing a combination of electronic and mechanical center differentials mated with yet a third planetary gear-type differential , the standard all-wheel-drive setup now defaults to a slightly rear-biased 41:59 torque split, but that split can vary continuously up to a lock of 50:50. Why two center diffs? Subaru tells us that the electronic differential allows finer control of the front-rear torque split based on the intricacies of yaw rate, steering angle, lateral-g, and more, while the mechanical differential is faster to react to changes in engine torque output. Together, they should create a system that is both sensitive and robust.
With power split between front and rear, it must next be split between left and right by a pair of limited-slip differentials: a helical-gear type on the front axle, and a Torsen torque-sensing electronically controlled limited-slip differential at the rear. On top of that, the 2015 STI features Subaru's new Active Torque Vectoring software, which uses bias braking to proactively split power between port and starboard when cornering. All in, I'm counting five total differentials shuffling power front to back and left to right.
Giving drivers control of that complex powertrain are the VDC stability and traction control system, the DCCD differential control system, and the SI Drive powertrain control system.
There are three levels of Vehicle Dynamics Control: The default is full traction and stability control, Traction mode (TRAC) disables traction and stability control but leaves the Active Torque Vectoring system active, and Off disables even the torque vectoring.
There are also three settings for the SI Drive throttle control system: Sport is interestingly the default setting for sporty driving, Intelligent uses a slightly less sporty throttle response for driving in inclement weather, and Sport Sharp (S#) is the most dynamic setup with the sharpest throttle response regardless of engine speed.
Finally, there's the Driver Controlled Center Differential, which features three automatic settings. Auto [+] emphasizes greater traction and is best for wet or slippery roads, Auto is the baseline setting for daily driving, and Auto [-] loosens up the vehicle's handling for quicker steering response and better rotation when cornering. If you don't like the automatic DCCD settings, there are six manual levels to choose from, ranging from Low, which is best for high-grip, corner-happy situations, to High (or Lock), which is best for slippery conditions or high-speed, straight-line stability.
That's a lot of settings to process. Thankfully, Subaru's engineers gave me a cheat sheet for the best settings: set VDC to TRAC (but not Off), SI Drive to S#, and DCCD to Auto [-] when you hit the track. On your favorite back road, leave VDC on and set SI Drive and DCCD to their default S and Auto settings, respectively. After a day of fiddling with the settings, I unsurprisingly found that the engineers knew what they were talking about.
Easier to wrap my head around were the chassis and suspension upgrades for the 2015 WRX STI. Simply put, the entire vehicle is stiffer. This includes the chassis, which boasts torsional rigidity that's 40 percent stiffer than the standard Impreza sedan, and the suspension, which is stiffer overall when compared to that of the outgoing STI model, with higher spring rates, stiffening plates, and more rigid bushings. The STI's steering is quicker than the standard 2015 WRX upon which it is based, and it retains a hydraulic power steering system, rather than making the jump to an electronic rack. Its rear suspension features slightly more rear toe-in, which further improves its turn-in responsiveness. And at the business end of that suspension are larger wheels shod with wider, stickier tires.
From the outside, the best way to tell a 2015 WRX STI from a lesser WRX is the massive rear wing that protrudes from the rear deck. Subaru tells us that this isn't just a styling choice; the wing contributes downforce at speed, increasing stability. On the bright side, it sits so high that you can see clear under it from the driver's seat, so at least it doesn't reduce visibility.
The track
With the performance parts fully explained, I donned my helmet and hit the track. Immediately I noted that I enjoyed the STI's deeply bolstered seats, which also now featured a higher back and adjustable headrest. Pedal placement was ideal for easy heel-and-toe downshifts, the standard shifter gave great feedback and positive engagement, and cabin visibility is quite good. The flat-bottomed steering wheel was the icing on the driver-focused-cabin cake, with a thick rim, but small racy diameter. The STI is a car that is easy to drive, its cockpit fitting my 5-foot, 9-inch frame like a glove.
Armed with my knowledge of how the all-wheel-drive system worked, I knew that the DCCD and the rest of the alphabet soup were shuffling more power to the rear axle and outboard midturn to help with rotation, and then shuffling it back to a perfect 50:50 split for maximum grip as I rolled onto the throttle post-apex. I knew these things, but I didn't actually feel them happening. Earlier in the day, drivers groaned when they heard of the STI's Brake Override System -- a new unintentional acceleration deterrent that prevents the car from accelerating when both the gas and brake are depressed -- but the addition of this system didn't hamper my ability to heel-toe downshift, a maneuver that specifically requires pressing the gas and brake pedal simultaneously while shifting. The STI's safety net almost never shows itself when you're just going fast, which made me feel comfortable and encouraged as a driver to just go faster.
And go faster I did. With tons of power on tap and gobs of grip, I often found myself rounding the familiar corners of Mazda Raceway sometimes an entire gear faster than I thought I'd be comfortable with. For example, just after the near vertical drop of the track's signature turn, the Turn 8 Corkscrew, is the deceptively fast downhill left-hand Turn 9. I've found this corner tricky to master (enter too quickly and understeer off of the track, but panic and lift the accelerator midturn and you'll spin) and always approach it with caution in front- and rear-drive vehicles, but was able to be more aggressive, thanks to the STI's generous limits and confidence-inspiring handling.
Around the race track's many corners, I was pleased to note how readily the WRX STI's chassis rotated around a central axis in reaction to my steering and throttle inputs. It doesn't so much "go where you point it" as it "goes where you intend it." It's that good. I found myself giggling with glee while the Subaru coaxed me to push just a bit harder next lap.
The safety net is nearly transparent, but it did assert itself when I ran out of talent. On my frustration-fueled charge into Turn 2 early in the day, I found myself carrying too much speed into the hairpin. Braking hard and late, I was pleased with how efficiently the upgraded brakes shaved the speed down to nearly manageable velocities. I was preparing face the embarrassment of understeering into the gravel when I noticed that the car was actually turning -- the all-wheel drive system finding grip here, slowing a wheel there, and getting itself where I needed it to be. The Subaru had saved the day with a quiet encouragement to "do better next time" rather than scolding me with a "don't do that."
About a second after erring, I was back on the accelerator, the rear end of the Subaru dancing ever so slightly wider than the nose, and back on the racing line as I completed the turn. Danger was behind me and open track lay ahead.
The road
It should come as no surprise that the WRX STI rides roughly over cracked pavement. It is a sport special edition with a stiff suspension so you'll have that, but I expected a car with this much rally racing cred to soak up uneven pavement with more poise. As is, the STI's ride was almost too stiff for San Francisco's cracked and craggy streets. Despite battering me and my passengers mile after mile, the STI itself never seemed too upset by midturn bumps, cracks, or potholes, so I'm thankful for small favors. The deal that you make when you choose this Subaru is to trade a lot of daily driving comfort in the pursuit of performance, so STI drivers should know what they're getting themselves into. Just be careful what you wish for.
The broad torque curve of the 2.5-liter turbocharged engine results in easily accessible power both on the track and on the road, while the six-speed shifter felt good when poking around town.
A short-throw shifter is available, which I was able to sample, but I think I'd prefer the standard rower on my daily driver. The standard shifter is already technically a short-throw shifter when compared with the standard WRX's -- at least, that's what Subie's engineers told me before tossing me the keys. The optional shifter is then a "ridiculously short throw shifter," in my opinion.
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The tech
The good visibility afforded by the generous greenhouse are even more useful on the road than they are on the track, and a standard rearview camera and small dashboard display help greatly when reversing or parking. When it's not being used for reversing, the color dashboard display can be used to display a turbo boost gauge, an all-wheel drive information graphic, fuel economy information, and more.
Of course, the Boxer burble and slight whine of the turbocharger can be better appreciated at more moderate street speeds. Which is good, because the stock audio system is pretty disappointing. The functionality of the simple, two-line LCD display is fine; all 2015 WRX STI models come standard with Bluetooth hands-free calling and audio streaming, HD Radio tuning, satellite radio, and USB connectivity, a respectable loadout of audio sources. However, the standard six-speaker audio system just isn't up to the task of filling the STI's loud cabin with audio. I found that I needed to crank the audio to nearly maximum to hear it clearly at highway speeds, at which point, the bass began to distort unpleasantly.
The WRX STI optional Harman Kardon audio system sounds so much better, filling the cabin with thump without neglecting the higher end of the audio spectrum. If your 2015 STI isn't packing this nine-speaker, 440-watt option, you're better off just rolling the windows down and enjoying the exhaust note.
None were on hand during either of my test drives, but the WRX STI will be available with an optional navigation system with Aha Radio smartphone integration. I wasn't particularly wowed by this system in the 2014 Subaru Legacy, so I'm not too excited about seeing it again in the STI.
On the exterior, you'll also find that the headlights have been upgraded to LED illumination.
The competition
The all-wheel-driven WRX STI occupies an odd space in the automotive world, there's not much that it competes against. Audi's smaller performance models get priced nearly out of the class. The Golf R is, well, the Golf R. The awesome Mitsubishi Lancer Evolution X is the biggest danger to Subaru, but it hasn't been significantly updated in almost a decade. (Plus, you're probably either a Mitsubishi guy or a Subie guy. I'd imagine that few fanboys are cross-shopping this rivalry.)
The 2015 Subaru WRX STI starts at $34,495 before adding a $795 destination charge. The only option worth mentioning is a $2500 tech package that upgrades to the Harman Kardon audio, GPS with Aha app integration, and keyless entry and push button start. Our example wasn't so equipped, putting our as-tested price at $35,290 -- a nearly $10K premium over a similarly equipped Subaru WRX.
For the last generation, I felt that the standard WRX was enough car and that the performance upgrade to STI was only worth the massive price premium for drivers who regularly participate in club track days, autocross events, and other motorsports. While I wasn't able to do back-to-back testing between the 2015 WRX and STI models, I've got a hunch that my opinion won't have changed for this generation. The 2015 WRX STI is a spectacular car, but it's more car than you'll probably ever use on the road. To suggest less power is blasphemy, I know, but the standard WRX's lower price, better fuel economy, and still potent performance earn it my nod for daily-driven rally car.
Of course, if you live in the land of glass-smooth roads and plentiful racetracks, feel free to ignore my advice.
| Tech specs | |
| Model | 2015 Subaru WRX STI |
| Trim | base |
| Powertrain | 2.5-liter Boxer four-cylinder, six-speed manual transmission, Symmetrical All-Wheel Drive, Driver Controlled Center Differential, Vehicle Dynamics Control |
| EPA fuel economy | 17 mpg city, 23 mpg highway, 19 mpg combined |
| Observed fuel economy | 16.8 mpg |
| Navigation | Optional, not equipped |
| Bluetooth phone support | Standard w/ audio streaming |
| Digital audio sources | USB, 3.5mm analog auxiliary input, CD, Bluetooth audio streaming |
| Audio system | Six speakers |
| Driver aids | Standard rear camera |
| Base price | $34,495 |
| Price as tested | $35,290 |