With just 500 Vipers set to be produced before the current model ceases, American manufacturer Chrysler promised something special for the final batch of cars. Well 640 bhp certainly sounds special for this ‘track only’ SRT10 ACR-X, which will make its debut in the spring of 2010.

Priced at $110,000 (you can pick up a road-legal SRT10 ACR for $103,000), The Viper is powered by the infamous 8.4 litre V10, producing 640 bhp, which is 40bhp more than the regular SRT10 ACR (American Club Racer).

The suspension is tuned and upgraded specifically for on-track usage, whilst the weight is reduced by a full 71 kg (160 pounds) compared to the standard production Viper to take on even the most challenging tracks. Additional aerodynamic upgrades improve downforce, while enhancing stability and significantly improving grip in high-speed cornering.

Last month, the SRT team used a testing session at Laguna Seca raceway to shake down the Viper ACR-X for the first time. Behind the wheel was professional driver Kuno Wittmer from the SCCA Pro Racing SPEED World Challenge Touring Car Championship series, who was able to run consistent 1:31.00 lap times around the 2.238-mile, 11-turn track. Wittmer’s lap times were more than 3 seconds faster than the street-legal Dodge Viper SRT10 ACR that holds the production car track record at Laguna Seca raceway.

“The Dodge Viper ACR-X is incredible,” said Wittmer. “After a short warm up, I was running lap times as quick as exotic GT race cars. I was blown away by the power and acceleration, and even more surprised at how the ACR-X navigated the challenging Laguna Seca corners and how friendly it was to drive at the limit.

“All aspects of the car work together perfectly to plant all that horsepower and torque without issue,” Wittmer added. “This will be a great package for someone coming out of grassroots racing with a desire to step-up to GT level competition. Dodge nailed it with this one!”

The Viper SRT10 ACR-X is designed to compete in the Viper Racing League, Sports Car Club of America and National Auto Sport Association events.