The long-promised future of driverless cars is closer to our driveways than ever. A testing site for the new automotive technology opened Monday at the University of Michigan in Ann Arbor. The 32-acre site called Mcity was built to resemble a small town, complete with a tunnel, roundabout, and highway exit ramps. More than a dozen companies can sign up to test their products on the site in order to make driverless vehicles safe for the road. The federal government has estimated that such cars could cut down on crashes by 80 percent.