You don’t know boredom until you’ve had a ride in Subaru’s Global Rallycross (GRC) car.

I should explain: riding shotgun while a driver man-handles 600 horsepower over dirt and track, bounding jumps and sliding sideways for 10 minutes straight, is a greater thrill than being dumped off the side of an airplane for a 10,000-foot plunge. It’s the day after that’s rough.

Coming down from that kind of high is like falling into a pool of mud: getting clean takes a very long time. Even after your muscles release tension (in my case, a full day later), the act of driving, or walking, or moving in any way feels painfully lethargic.

The smile etched on your face for another 36 hours would have people believe you’re walking on air, but inside you feel listless and disoriented. By day three, you find yourself researching spicy wing competitions and rock climbing gyms – something, anything to jumpstart the emotional respite.

Subaru Global Rallycross

Subaru GRC

I would be angry if I wasn’t so damn impressed. Recalling the blur of action that was my lap and a half of GRC’s Port of Los Angeles course, two things stand out: 1) a permanent lack of traction, and 2) Chris Atkinson’s multi-tasked precision.

Much like American Flat Track racing, GRC cars operate almost exclusively sideways in a race. Even for the brief interval when a car is pointed in a straight line, it is still spinning its tires in a desperate search for grip. All the while, drivers are yanking on an e-brake, shifting gears, left-foot braking, avoiding obstacles (other cars, walls, etc.), and measuring throttle input. Watching this kind of frenetic dance from the grand stands is a hoot, but sitting in the middle of it is mesmerizing.

I could belabor my awe, but thanks to the power of video, you can form your own conclusions about GRC’s tenacity. Here’s my ride with Subaru Rally Team USA (SRTUSA)’s Chris Atkinson:

Subaru Rallycross

We’re about to go for a RIDE in a Subaru Rally Team USA GRC race car! 600 horsepower and 0-60 in 2.0 seconds! Get ready. #srtusa #grc

Posted by Digital Trends on Friday, October 13, 2017

Following the ride, I was shoehorned from my bucket seat and pointed in the direction Subaru’s tent. With tremendous focus, I shimmied my legs in crude interpretation of walking. After plopping onto a bench, draining four water bottles, and circulating a good amount of new air, my brain flickered to life.

To my right, SRTUSA engineers hurriedly adjusted one of the two WRX STI-based race cars. To the untrained eye, a GRC car might just be a wide-bodied production vehicle. My experience suggested otherwise. Tracking down a member of the SRTUSA team, and later the team’s GRC drivers, I (politely) asked what the heck was going on.

What are some of the key differences between the 2018 Subaru WRX STI production car and these GRC race cars?

Chris Yandell (of SRTUSA): We start with a stock 2018 Subaru WRX STI and then make a wide range of modifications. These cars take several thousand man-hours to build and are worth north of half a million dollars.

We build the cars to the latest Red Bull GRC rulebook, which allows for a lot of performance and durability modifications. The GRC cars produce nearly double the HP of the road car, making approximately 580 hp and 650 pound-feet torque with GRC Mandated 45mm turbo inlet restrictor. To produce that sort of power reliably and with a wide, usable power band, the engines are custom made with many bespoke parts. We do all of that in house.

The cars reach 0-60 mph in 2 seconds, have sophisticated turbo anti-lag systems and launch control. The all-wheel drive system is not too different from the road car, but GRC cars are much more robust in order to deal with all the power we put down.

Subaru Global Rallycross

Subaru GRC

There are extensive modifications to the chassis to lighten the car and allow for revised suspension geometry and travel. We also mount the radiator at the rear of the car to protect it from mud and car-to-car contact. RX cars (GRC builds) are easily distinguishing from a rally car by the large air inlets in the doors and the large trunk cutout (rally cars will keep the radiator up front).

Another big difference is that the road car’s exterior bodywork is replaced with custom panels that are made of a variety of composites (carbon fiber, carbon Kevlar, etc.). Nearly every panel on the car is custom and designed to accommodate the wider track, be more aerodynamically efficient (downforce) as well as be more durable/robust since there is so much car-to-car contact.

Tell me a little about the symmetrical all-wheel drive (AWD) system. What sets it apart from the more electronically controlled AWD systems in some competitor vehicles and how is it optimized for this GRC car?

CY: The road going STI has helical/Torsen limited-slip differentials (LSD) in the front, a clutch-type center differential with an electronic controlled clutch pack (they call it DCCD – driver controlled center differential), and a rear helical/Torsen LSD. In the GRC cars, the front and rear are clutch type LSD and are more tunable/robust compared to Torsen style, which allows us to tune the AWD setup more. While the GRC car’s center differential performs very similar to the road car’s, we don’t have the electronic controlled option because they are banned in GRC.

How did this year’s GRC cars change from last year?

CY: We built a new chassis this year that was lighter and moved the weight lower and more toward the center of the car. This really helps with the handling of the car in all areas.

Subaru Global Rallycross

Subaru GRC

We were also able to increase the suspension travel and made some other small changes to suspension geometry. The cooling package was redesigned a bit based on things we learned last year. The engine has been developed more and makes more power and has a wider power band. All in all, the car is quicker and easier to drive.

Now that I understood how the machine worked, I had a few questions for the men tasked with driving it

How do you like competing in GRC? How would you compare this to traditional/stage rally driving?

Chris Atkinson: This has been a big learning year for me, and I think it will really set me up for the future. Not only do I think the car can be faster, but I still have more growing to do as a driver. To this point I have only done 11 weekends of rallycross racing in my life and every weekend I learn something more.

SRTUSA

In stage rally (forest rallying) you are a lot more reliant on your own performance, where rallycross is a bit more unpredictable. You can be the fastest guy out there and still have a really bad weekend, through the actions of others. But that’s the game and you have to deal with it.

How would you compare this year’s performance to last year’s?

CA: The work the team has done to improve the car has been the most important part in this success, putting a package together that could be really competitive and then working hard to maximize it. Last year a podium was a hope, but not reality. This year podiums were inevitable and it became a disappointment if we didn’t achieve one. That only comes about with speed and having a fast and competitive car, which Vermont Sportscar/SRTUSA have developed.

Subaru Global Rallycross

Subaru GRC

How do you like racing with Subaru?

Patrik Sandell: I absolutely love my first year in GRC with Subaru. I’ve been in the sport for many years now and I feel I’ve been able to bring my experience behind the wheel to the team. We’ve grown together quite a bit this year.

We hear you operate a rally school in Sweden that uses old Porsche 911s. We also hear you race in seal skinned boots. Tell us more!

PS: My GRC spotter, Mattias, and I are running FlatOut Sweden, offering a lot of different driving experiences through our partners (including Tuthill Porsche). Yes, it’s true my seal skinned boots are the best racing shoes for winter conditions. We are also working on setting up a location for ice driving here in the states!

600 horsepower is a monstrous amount to handle. What’s it like to wield that kind of performance on such varied terrain?

PS: My Subaru is actually very easy to drive. It’s built to go fast and gives me the confidence to win races.

CA: I think most people wouldn’t understand the finesse required to drive these cars; very rarely can you use all of that 600hp. It’s like trying to tame a wild beast: you have to really be calm and relaxed, then, when its ready, you can unleash it all.

Subaru Global Rallycross

How would you characterize GRC fans compared to fans of other motorsports?

CA: You can see it’s a young, enthusiastic crowd — people who want action and don’t want to sit around all day watching cars follow each other. They want to see passing and contact and exciting races; that’s exactly what Rallycross gives you.

PS: GRC and, specifically Subaru fans, are absolutely awesome. The passion they show for drivers, the brand, and the sport is above and beyond!