The American Club Racing (ACR) model was introduced in 1999. This model had suspension and engine enhancements focused on maximizing performance in road racing and autocross environments. A new ACR was added to the Viper line-up after the 2008 model year. Its upgrades were more drastic than the original, including street-legal racing tires (Michelin Pilot Sport Cups which Michelin describes as “Ultra-High Performance Sport tires”). The ACR is street-legal, and is similar to the MOPAR Viper that Dodge displayed at various auto shows. The Viper ACR was built alongside the standard SRT-10 at the Conner Avenue plant in Detroit. The aerodynamic components were produced by Plasan Carbon Composites and assembled to the vehicle by Prefix Corporation located in Rochester Hills, Michigan.