http://www.freep.com - Cadillac's semi-autonomous driving system passes 880-mile highway test with flying colors. Cadillac is about to change what driving is like. For the better. I just drove 420 miles of interstate highway and had a hand on the steering wheel for perhaps 20 miles. I touched the accelerator or brake pedal perhaps a dozen times in the course of more than six hours behind the wheel. The rest of the time, I chatted with my companions, admired the scenery and relaxed, courtesy of Super Cruise, a new technology available this month on the 2018 Cadillac CT6 luxury sedan.