Researchers in America say we could start seeing the benefits of autonomous cars when only a few of them are operating on roads, because they will reduce so-called phantom traffic.Website witf.org reports that research by Benjamin Seibold of Temple University in Philadelphia suggests that jams caused by cars braking suddenly might be solved by self-driving cars."What our study showed is, it only takes about five percent of the vehicles being equipped with smart, adaptive cruise control systems and having some connectivity to actually have a substantial impact on the overall traffic flow," he says.He and a team of researchers ran an experiment with about 20 cars on a circular track and found there only needs to be one driverless car in the circuit to avoid jams.The report also says improved traffic flow in the experiment cut fuel consumption by 40 percent.