Beyond its considerable suspension upgrades, the ACR also receives large carbon-ceramic brakes and the largest overall tire footprint you'll find on a new car. The rear wing that comes as part of the optional aerodynamic package is also sized to the extreme, as it stretches more than 6 feet wide.
Where other track-oriented cars have automatic transmissions and electronically controlled hardware, the ACR package is refreshing in its simplicity. Antilock brakes and a five-mode stability control system are the only electronic driver aids.
What's Different Under the Hood?
Nothing. The 8.4-liter V10 and six-speed manual transmission in the ACR is the same setup used in all Vipers. There's a reason it was left unchanged: It already makes 645 horsepower and 600 pound-feet of torque. And while its displacement and two-valve pushrod architecture might make you think this is a low-revving truck engine, it actually produces peak torque at a lofty 5,000 rpm.
What's New for the Chassis?
The Viper ACR is singularly focused on track performance, so there were no compromises made for street comfort. Case in point, the spring stiffness is tripled front and rear versus the standard model, while the wheels take on significantly more negative camber (inward tilt of the tire versus the road) to aid cornering.
Atop the new Bilstein coil-overs are twistable rings that offer 10 settings for bound (how much the damper resists spring compression) and rebound (how quickly the damper lets the spring expand), allowing you to tune the ride to varying track surfaces. Adjustable spring perches also let owners adjust the ACR's ride height as much as 3 inches. This also permits corner balancing, which controls how much of the vehicle (and driver) weight pushes on each wheel.
The Brembo-supplied carbon-ceramic brakes offer stronger and more consistent stopping power, but require a few changes. An additional cooling duct helps the 15.4-inch rotors and six-piston calipers up front dissipate heat, while the sheer size of the rotor itself necessitates larger, 19-inch front wheels.
Those forged aluminum wheels are wrapped in Kumho Ecsta V720 tires specifically designed for the ACR. In fact, they wear the ACR logo right on the sidewall. The 295/25 front and 355/30 rear tires, when combined, offer the widest tire footprint of any street-legal car available today. Their large tread blocks and sticky compound make for excellent grip, yet Dodge claims they'll last for extended lapping sessions.
How Does the Aerodynamic Package Work?
When equipped with the aptly named Extreme Aero package, the Viper ACR gives up straight-line speed in order to boost downforce to increase cornering grip. Where the standard Viper's top speed is 206 mph, the Aero-package-equipped ACR can only attain a measly 177 mph. On the flip side, it's generating well over 1,700 pounds of downforce at that speed.
Yes, that's some serious downforce, so much in fact that the vertical strakes on the rear diffuser will scrape the ground at full push. Fortunately, these parts are designed to be replaced.
The Extreme Aero package consists of a long extension to the front splitter, dive planes on the sides of the fascia, louvers on the hood, a monstrous rear wing and the low-hanging rear diffuser. Most of the components are adjustable and removable, all in the name of giving owners the ability to tailor their car's balance to various racetracks.
What Is It Like To Drive?
Don't confuse the ACR's high levels of performance with a nasty attitude. Its racecar-inspired hardware doesn't come with typical racecar quirks or intimidation. The added downforce, suspension upgrades and sticky tires offer extremely high limits without any loss of tractability. It doesn't feel snappy, and the brakes and tires don't turn on and off due to temperature.
Ultimately, the hardest thing about driving this Viper is acclimating to how fast it can go through corners. We had six laps at Virginia International Raceway's 4.1-mile Grand Course to get a feel for the ACR's potential.
A section of high-speed esses on the first section of the track provided a good demonstration of the cornering forces it can deliver. We approached cautiously on the first lap, holding 90 mph through the section. By the last lap, we had the confidence to go through at 125 mph. The ACR stays settled when it bounces off rumble strips, and its capabilities only grow as speeds increase.
There is immense power at your disposal, but it's easily managed. The steering is quick and precise. The shifter slides into gears in a positive, satisfying motion. A long gas pedal helps dole out power in small increments and it's positioned well for heel-toe downshifting. The huge tires and carbon-ceramic brakes produce immense stopping power, and you can feel the downforce bleed off the car when you're braking from 140 mph.
What's the Interior Like?
Besides the shifter, pedals, steering wheel and seats, the rest of any racecar's interior offers little value on a track. With that in mind, Dodge pulled most of it out in the name of saving weight.
The normal carpeting is gone, there's no sound-deadening material and the stereo was reduced to a minimum. Pop the hatch and you'll see bare plastic and ducting in the trunk. This car is serious about speed and not much else.
It does get a few touches that are unique to the ACR compared to the standard Viper models. An Alcantara-covered steering wheel is one of them, along with ACR badges. There's a choice of red or white stitching, too, for the Alcantara-lined dashboard.
Can I Get It With Leather?
If the idea of getting the most radical Viper ever built appeals to you, but having no radio doesn't, there is one option. Dodge's new "1 of 1" program allows buyers to build a Viper in almost any configuration they want. You think leather seats and a Harman Kardon stereo would make the ACR that much better? They'll build it for you. Same goes for the paint, the wheels and even the stripes.
How Much Does It Cost?
The Viper ACR starts at $122,590 (including a $2,495 destination charge and $2,100 gas-guzzler tax). Adding the Extreme Aero package will set you back another $6,000, while the carbon-fiber package is another $5,100.
What Competing Models Should You Also Consider?
The factory track-day special is a rare offering. On the lower end of the spectrum is the Chevrolet Corvette Z06. It starts at only $83,000, but adding the Z07 aero package and a few other choice options will push its price to nearly $100,000. Its 650-hp supercharged V8 has plenty of punch, although its suspension doesn't offer quite the same level of customer adjustability.
On the high end, there's the $176,895 Porsche 911 GT3 RS. It has several high-tech features like an electronically controlled differential, four-wheel steering and a dual-clutch automatic transmission. It's interesting hardware, but it's not for buyers seeking a less computer-aided approach to going fast around a racetrack.
Why Should You Consider This Car?
The Viper ACR delivers the most extreme track-focused experience of any street car on the market. If tinkering with your chassis and aero settings to find the perfect setup for your home track sounds like fun, you will find nothing better from the factory than the ACR.
Why Should You Think Twice About This Car?
This is more than just a Viper with a big wing on the back; it's a barely street-legal racecar. Although technically capable of functioning as a daily driver, its extreme tuning makes it ill-suited for the street.
Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.
