Q&A with Todd Hill
Drive Performance (DP): We wanted to get to the bottom of the handling story right away, so we asked, “Todd, you told us that handling was key for the WRX. How did that impact the engineering of the new WRX STI?”
Todd Hill (TH): “In terms of the handling, there’s a faster steering ratio. WRX gets quicker, WRX STI gets quicker, too, but more so!”
He added that the quicker steering ratio and more rigid system on the WRX STI really ratcheted up steering precision. The changes help sharpen vehicle turn-in (the transition between driving straight ahead and cornering). Stronger bushings for the steering box, as well as increased torsion-bar rigidity, enhance responsiveness for a more direct steering feel.
“One of the big parts of the suspension tuning is how quickly it responds to you turning the wheel,” Hill said. “Subaru put in a lot of effort tightening the steering rack and suspension system.
“The handling limits are a little higher, but the feeling of the car is so much quicker. It’s more immediate and precise.
“On the suspension – everything is tuned for STI. Springs, dampers, tuning, sway bars, and, on the front, the inverted struts – those are the big differences in the car, plus the stiffer body.
“The body is beefed up. All the places where the chassis flexes have been strengthened or have added support, especially over the suspension mounting points. We’ve really tightened down the body to stop the flex and movement within the suspension.
“That lets us run stiffer springs and a stiffer suspension system, but it can still absorb an impact rather than the whole body quivering after hitting a bump. It’s just a ‘Thump!’”
What the Heck Is Active Torque Vectoring?
DP: “With the body and suspension bolstered to improve handling, were there any changes in the electronically controlled chassis-management technology?”
TH: “We pick up Active Torque Vectoring, which is awesome. When you go into a tight turn, as you’re turning the wheel, you’re thinking, ‘I’m going to turn more.’ And it can’t possibly have any more to give. It just can’t. But it just keeps going in. The grip is just ridiculous! However much you think you have, it’s got more to give.
“Some of that is because of the Active Torque Vectoring, and some of it is from the suspension tuning. Torque Vectoring is good, and it’s quick.”
DP: “So what kind of upgrades were given to the engine? We hear it’s more responsive.”
TH: “We changed the ECU tuning and made some other refinements. As a result, the engine is a lot more responsive. So the engineers say it feels like a brand-new engine, even though it’s not. It’s more ready-to-go, more reactive.
“Acceleration is the same as the current car, and its power-to-weight ratio is still best in class.
“We also added the sound creator. It’s the same thing we did in BRZ. It brings some engine sound into the cabin, adding to this car’s cool factor. There are no electrical components involved. It’s a purely mechanical system.
“There’s a tube in the air intake, and it goes to the sound creator. Inside it, a damper – a diaphragm – filters out undesirable frequencies and passes desirable ones at certain accelerator positions – mostly with more accelerator. That engine sound goes into the cabin.”
DP: “It’s good to hear the WRX STI still has go-power. What about stopping power? We know the 2015 WRX has a number of changes in its brake system. Are there changes for the WRX STI?”
TH: “The car still has the Brembo®1 system. But the brake booster, master cylinder, override system – those were all upgraded or improved. That’s going to give you better brake feel.
“Wheels – a little bit more rigid, and that’s going to help the handling, too. They’re lighter. The forged alloy wheels are just as stiff and a little lighter yet.”
DP: “With the mechanicals adding even more performance for 2015, there must be some interior upgrades as well. How did Subaru set up the inside to appeal to enthusiasts?”
TH: “The WRX STI has red highlights, Alcantara®2, and stitching on the door.
“Other cool things include the lower belt line, improved visibility, a lower instrument panel, and pockets. WRX STI guys don’t necessarily care about that stuff, but it makes travel more comfortable.
“The steering wheel is smaller; it has a D-shape design. The seats are the same as the WRX except for the materials. Color is the same.
“The Harman Kardon®3 audio system is a big deal for us. People have been asking for premium audio on the WRX STI, and it’s a really good system. Just to highlight how much effort went into it – tuning the sound to the car took somewhere around 300 hours!”
Hill gave us information about the special Launch Edition while we were with him. He’s proud of it because it has strong ties to the WRX STI models with which we first fell in love.
What can you tell us about the Launch Edition?
Todd Hill gave us this overview: “We have a limited number – a thousand units. We’re going to build them over the first three months. They’re all blue. They all have gold BBS wheels – they have to be BBS wheels for this car.
“The interior highlights are blue instead of red. It has Keyless Access and Start – push-button start – and a short-throw shifter. This Launch Edition falls between the base and the Limited.
“It’s a little bit of a throwback to the old days, but nothing too crazy.”
Find more WRX STI specs, dimensions, and features.
The introduction of a performance flagship like the WRX STI doesn’t come along very often, and waiting can make your imagination go wild. Listening to Todd Hill describe the car’s highlights got our blood pumping. But as Hill said in the beginning, “Wait till you drive it!”
Check out the car and its handling at your Subaru retailer!
1 Brembo is a registered trademark of Freni Brembo S.p.A.
2 Alcantara is a registered trademark of Alcantara S.P.A., and Alcantara is produced by the Toray Group.
3 Harman Kardon is a registered trademark of HARMAN International Industries, Inc.