A Navistar spokesperson confirms that these these are known as “Q” (Quality) builds, which were built in Escobedo, Mexico. These units are used to validate production designs and processes. These four Q builds follow 16 validation vehicles that were built at our Test and Development center in Melrose Park, Ill. These 16 trucks have been accumulating miles in field tests and a validation fleet. Navistar says these trucks have accumulated more than 55,000 test miles, with more than 100,000 miles expected by the end of September.