Today, Amazon will start delivering packages to parked cars. The rollout is available in 37 U.S. cities to those who have the proper technology in their vehicles – 2015 or later models of Chevrolet, Buick, GMC, Cadillac or Volvo cars equipped with roadside-assistance technology. The service allows a courier to pop the trunk or open the back door with help from a smartphone. Packages are then dropped off in the trunk or left on the back seat. Amazon hopes to expand the service to other car makers over time.