MADISON, WISCONSIN – Most cars on Wisconsin roads will be driverless two decades from now, a University of Wisconsin researcher says. "They're coming, whether we like it or not," engineering professor David Noyce said at an Assembly committee hearing on the future of autonomous cars Wednesday. Driverless cars can make driving safer, cut traffic, reduce emissions and give more people the ability to get around, according to Noyce and others who testified. But many challenges remain: bad weather and hackers can throw off the technology, the cars are pricey and legal questions remain, such as who is liable when something goes wrong. Last month, the University of Wisconsin-Madison Traffic Operations and Safety Laboratory was one of 10 groups nationwide the federal government designated to test the vehicles.