Many systems depend on accurate location information from Global Navigation System Satellites (GNSS) for normal operation. Public GNSS lacks integrity mechanisms and is vulnerable to spoofing. U.S. Federal law does not allow over-the-air spoofing of GNSS or other signals, which makes assessment of vulnerabilities difficult outside of an enclosed laboratory environment. This research proved the usefulness of a Mobile GNSS Spoofing System that enables legal, real-world evaluation of GNSS vulnerabilities. The mobile spoofing system was used to evaluate vulnerabilities in an Unmanned Ground Vehicle (UGV). The UGV GNSS was exploited using several different attacks including forced lane switching, driving off the road, and stopping the vehicle.