U.S. consumers still resist the notion of self-driving cars, according to a University of Michigan study released on Monday, the latest sign that investors and automakers may be rushing into a business where demand is limited at best. General Motors Co's recent acquisition of Silicon Valley startup Cruise Automation for a reported 1 billion has accelerated a stampede by other automakers, suppliers and venture capital firms looking to invest in or acquire new companies developing self-driving technology. Consumers, meanwhile, remain concerned about aspects of self-driving technology and "overwhelmingly" still want the ability to manually control a self-driving vehicle, the study said. "The most frequent preference for vehicle automation continues to be for no self-driving capability," said the study's authors, Brandon Schoettle and Michael Sivak. The survey results are consistent with those in a similar survey that the university conducted a year ago and generally mirror the findings in a study that the American Automobile Association released in March.