United States, May 12 -- One of the most exacting General Motors customers - the U.S. Secret Service - is testing a fleet of 10 of our vehicles at their James J. Rowley Training Center in Laurel, Maryland.The agency said in a post on its website that they've taken delivery of two Cadillac CT4 sedans, two Cadillac CT5 sedans, two Corvettes, a Cadillac Escalade SUV, a Chevrolet Colorado pickup, a Chevrolet Tahoe with a police package, and a Chevrolet Suburban SUV.In their announcement, the Secret Service said that instructors in the agency's Protective Transportation Section have been asked to provide feedback on technology integrated into the newly acquired vehicles. The Secret Service also said that having a variety of vehicles on the train...